It wasn't so much "Star Wars" itself that inspired ABC's "Battlestar Galactica," to be realistic about it, as it was the success of "Star Wars". Most prime-time entertainment is derivative of something, and that something is often somebody else's smash hit.

The pleasant surprise about "Galactica," which premiers with a spectacular and captiviting three-hour episode Sunday night at 8 on Channel 7, is the number of other influences that have gone into the creation of the program - everything from "The Fall of the Roman Empire" to "Fiddler on the Roof," from "How the West Was Won" to the Bible.

And, oh yes, "Roots." It seems "Battlestar Galactica" is a genealogical epic as well as a spirited and rousing adventure story. It unravels the history of a mirror-image human race which exists, according to the edict of the celestial sonorous narrator, in another solar system "somewhere beyond the heavens." Way up high.

In no way does "Galactica" duplicate the enlightened escapist brilliance of "Star Wars." It doesn't have the wit, the whimsical personality, or the exhilirating pace. "Star Wars" was a masterpiece of instant mythology; "Battlestar Galactica" must settle for being merely a handsome, engrossing, supe-duper television show.

John Dykstra, who supervised the special effects for "Star Wars," produced the first "Galactica" and also coordinated its special effects. So there are zippy, trippy space battles and the most impressive display of special effects hardware and ersatz explotions ever seen in a fantasy television program.

What writer and executive producer Glen A. Larson has contributed is a pop-cultural pastiche that deploys nearly every conceivable family-baiting gimmick in the traditional television repertoire, plus a few more from other sources. It works amazingly well. "Galactica" may be essentially humorless but, to its credit, it actually has fits of dramatic impact that are more powerful and even more convincing than those of some TV program-s with far more recognizable settings and intrinsically empathetic situations.

When it was announced that former "Bonanza" patriarch Lorne Greene would play Adama, commander of the Battlestar Galactica, loud moans of "oh, no," did seem to be in order. The casting now appears a stroke of genius; Greene brings an unmistakably residual authority to the role that helps keep the program cohesive, despite the visual schism between the special-effects outer-space scenes and the more mundame interiors of the Battlestar shot on the soundstages of Universal Studios.

As his son, Capt. Apollo, Richard Hatch has the acceptably ineffectual appeal of many young TV actors, but sidekicks Dirk Benedict as Lt. Starbuck and Herb Jefferson as Lt. Boomer unfortunately emanate straight from the bottom drawer. Their fly-boy badinage, one of the few elements of the script too obviously scribbed from "Star Wars," comes off limp and flat, like the tedious small talk of the colorless ciphers who populated shows like "Emergency" and "Adam-12."

Among the women on board, however, Maren Jensen and Randi Oakes are considerably more life-like, and Laurette Spang is touching as Cassiopea, and outcast "socialator" who, apparently to appease the dullards in the ABC Standards and practices department, is prevented by the script from ever actually socialating with a member of the opposite sex.

Some of the sets are impressive and some suggest corners cut. Costumes worn by the governing "Council of 12" adhere to the Hollywood notion that people in outer space would for some reason dress like those in movies about ancient Rome; it's a toga party for old-timers like Lew Ayres and Ray Milland.

The plot of the premiere makes a good story, and it would be a shame to give it all away. Basically it tells how our distant brothers and sisters are lured into false hopes of armistice with their dread enemies, the Cylons, a breed of artificial being created eons earlier ("centons" earlier, in the Galactican vernacular) by a reptilian society, and now clearly out of control.

On the very eve of peace, their treacherous "Imperious Leader" looks down into their silver heads and redbeam eyes and proclaims "the final annihilation of the life form known as man."

Eventually all the planets housing humans, and the battlestars that offered them hovering protection, are destroyed - all the battlestars but one. Lorne Green marches to the mountaintop of a charcoal briquet that used to be a planet and announces, "Let the word go forth to every man and women that survive this holocaust . . ."

And with that he sets the stage for an exodus scene right out of Cecil B. DeMille. It's really kind of wonderful and full quasi-historical resonance.As with much science fiction, genuine or ersatz, the air is thick with allegory, metaphor and random reference. Greene even has "uneasy lies the head" speech reminiscent of Henry IV, and the fact that the phony peace conference is arranged by a traitor named "Baltar," which nearly rhymes with "Yalta," is probably not an accident.

This is not to say that the people behind "Galactica" have lavished it with profound thought or even with a great deal of imagination. In fact, many of the straight dialogue scenes directed by Richard A. Colla are as dull as the draggy as on any humdrum TV series. But you can sense that the people who did the effects have fun at their work, and this esprit spread spread to other aspects of the production.

The point is, perceptible creative enthusiasm is very rare in television and it helps make "Galactica" better than even the average stand-out.

There are some discouraging signs, however - particularly in a tacked-on "epilogue" that unwisely resurrects the presumably exterminated arch villain; "Galactica" may degenerate into a weekly game of outer-space cat-and-mouse with humanity as the mouse.

Or it may go the alreadt well traveled routes of "Star Trek," with its heavy-laden moralisms, or "Space: 1999," which had a similar odyssey format and whose characters simply loped along from one kinky society of menaces to another.

Whatever its future, "Battlestar Galactica" gets off on a grand right foot in its premiere. The idea that this fellow human race of ours sees its one hope for survival as reaching what Greene calls "a shining planet known as Earth" is a real charmer of forced naivete. Shining planet, indeed. Won't they be surprised?

After protests and proddings from activist groups that were followed by pious pledges of reform, the three TV networks have regressed back to the Flinstones age of Saturday morning children's programming. Cheap and insipid animation dominates all three network schedules, with CBS appearing to have done the very least possible in fostering new production of live-action shows.

Perhaps to save a fraction of its face, then the network's CBS News division today unveils "30 Minutes," an informational half-tour which hosts Christopher Glenn and Betsy Aaron starchily pronounce is "devoted to the interests and concerns of young people." When kids hear that formal offputer, they may head straight for a cookie jar on some other channel.

The first program - at 1:30 p.m. on Channel 9 - has filmed features on acne cures and on the rigors of forming a rock band, but the show comes across as stiff and chilly. Glenn shortens his name to "Chris" and uses phrases like "goofin' around" and "doin somethin' good," but these do not dispel the impression that this program is a product of committeeville and the CBS News is the biggest square since Ronald Reagan.

On the second program, though, there are two excellent reports produced by Jo Ann Caplin, the first a sobering look at juveniles who were tried and imprisoned as adults, and the second a contrasting jolly visit to the offices where "Mad Magazine" is published every 45 days.

The young men in prison interviewed Caplin and Glenn talk longingly and affectingly of the things that kill you the most," says a kid who suffers from dreams of being back home on the farm.

Glenn also brings up a prison hazard one may not expect to hear about on a show for young people - "the threat of homosexual rape."