Jimmy Connors, who thumbed his nose at the French Open tennis championships for five years after it thumbed its nose at him in 1974, returned to Stade Roland Garros today and made a triumphant debut on its center court.

He was received with the popular enthusiasm normally reserved for movie stars of the magnitude of Jean Paul Belmondo, who was in the gallery. Connors' appearance was a tour de force, even though his reception by the press when he arrived here last week was rocky.

Connors - seeded second behind Bjorn Borg, the defending champion and three-time winner of the world's most prestigious clay-court title - had to wait until after 6 p.m. on a gray, muggy afternoon to get on court , then needed only 95 minutes to rout a lesser American left-hander, Terry Moor, 6-1, 6-2, 6-3.

As far as the local mass media were concerned, this was the highlight of a long day that saw other matches considerably more competitive but no more dramatic single moment than Connors' grand entrance to a stage from which he had vowed to stay away indefinitely.

Connors, 26, played in the premier tournament of the continent twice before surging to the top of his profession. In 1972, he beat Spaniard Antonio Munoz and lost to Harold Solomon in the second round. In 1973, he lost in the first round to Raul Ramirez. He had never played a match in the imposing, steeply banked, 51-year-old center-court stadium with the salmon-colored clay court.

In 1974, the year he skyrocketed to the No. 1 world ranking, Connors won the Australian Open in January but was then barred from the Italian and French opens because he had signed a contract to play in World Team Tennis - then a first-year enterprise that was considered by Europeans a serious threat to their summer torunament circuit.

Connors went on to win Wimbledon and the U.S. Open that summer, and remains convinced that the European ban - inspired by French Tennis Federation President Philippe Chatrier - cost him the Grand Slam, a single-year sweep of the game's four major singles titles that has been achieved by only two men, Don Budge (1938) and Rod Laver (1962 and 1969).

It was an alleged conspiracy to keep him out of the French championship that was at the heart of the ill-fated $40 million antitrust suit filed on Connors' behalf in 1974. Connors' then-manager, Bill Riordan, knew it was impossible to sue in France, where there are no antitrust laws, but took the case of the celebrated French snub to America, where the complex and acrimonious case was eventually settled out of court in 1975.

It remains a matter of conjecture how much the lawsuit was Connors' affair, and how much Riordan's. But there is no doubt that Connors harbored a longstanding resentment of the French tournament, and his personal protest was not to play. He said he would play the French when he felt too old to win at Wimbledon.

But, apparently, all the animosities have been quite suddenly and unexpectedly forgiven and forgotten.

Connors - who may miss Wimbledon this year because his wife is expecting their first child in mid-July - applied two weeks ago for late admission to the $375,000 tournament.

Connors' arrival in Paris last week was big news.

After a short airport interview, Connors said he would answer more questions at his hotel, and that is where the troubles began. Reporters arriving there found no answer in his room, and cooled their heels in growing frustration and anger.

A free-lance writer hoping to arrange a long interview for an exclusive story in a Sunday paper dispatched the hotel's concierge to see if Connors was in his room. The man returned with a terse message: If the reporter was willing to pay, Mr. Connors was willing to talk.

This was interpreted, apparently incorrectly, as an ultimatum that Connors would do no interviews for which he was not paid. The reaction was immediate and indignant.

L'Equipe, one of Europe's leading sports dailies, ran a picture of Connors striding through the airport, cradling his rackets, with the headline: "Cache-Cash Jimmy," which translates roughly to "Cash-and Carry Jimmy."

Connor was portrayed in the media as a greddy, ungrateful mercenary. L'Equipe, in Monday's editions, carried a tongue-in-cheek schedule of tariffs for the privilege of talking to Jimmy Connors, much as one would find a schedule of fares and services on a card in taxi cab.

So it didn't take Connors long to strike up the same sort of rapport with the French press that he has long had with American knights of the keyboard. It didn't seem to faze him, just as it never has in America.

Nor did the bad publicity turn the French public against Connors, whose singularly physical style of tennis they have been waiting eagerly to see.

The stands at Roland Garros, enlarged this year to a capacity of more than 17,000, were nearly full today when Connors and Moor went on court - after two earlier matches in the stadium had consumed seven house between them. (Borg, who won here last year without losing a set, struggled to beat Tomaz Smid, 6-1, 5-7, 6-4, 6-4, and then Yannick Noah, France's Great Black Hope, outlasted Billy Martin, 7-5, 6-7, 6-2, 6-7, 6-3.)

Asked how he liked the playing surface that is anathema to so many Americans reared on fast courts, Connors was similarly aggreeable: "I love it . . . Je t'aime la clay," he said proving that his diplomacy is more refined than his French sentence construction.

"I'm going to try to play Wimbledon - I certainly want to," Connors went on, "but it all depends on my wife. I'll see how she's feeling, then decide."