A company of French paratroopers made camp here last night as part of the U.N. peace-keeping force after a deployment that gave them a quick introduction to the confusion, fear, waste, danger black humor and paradoxical beauty of present-day Lebanon.

Within hours after their jeeps and open trucks rolled out of Beirut airport onto the highway along the storm-tossed Mediterranean, 140 soldiers had seen Syrian army checkpoints, fleeing refugees, dirty children, armed Palestinian guerrillas, Israeli tanks, fruit rotting in abandoned orchards, the bloated carcasses of dead cattle, and luxury hotels occupied by destitute squatters.

The blue-helmeted soliders kept their rifles ready through this 50-mile crash course in Lebanon's unhappy reality. But Palestinian military police provided an unrequested escort into Tyre& and the only hazard the convoy faced along the way was the traffic - which brought the whole procession to a halt in the center of the town of Sidon.

Once here, the French set up temporary headquarters at a camp formerly occupied by the army of Lebanon. The army disintegrated during the Lebanese civil war, and the camp, already falling into ruin, was further devastated when the Israelis shelled it last week.

But the French almost had to fight for it anyway, as they arrived to find local Palestinian forces insisting that the camp was under their control.

The French commander, Col. Jean Salvan, a dashing, one-eyed veteran of France's colonial wars, entered into tense negotiations with the Palestinians.

Meanwhile, rifles were being cocked at the gates of the camp as the French nearly became embroiled in one of the characteristic violent disputes that often break out in Lebanon.

Two Lebanese officers - one claiming to be legitimate representative of the Lebanese army, the other from a breakaway Moslem-dominated faction called the Lebanese Arab Army - arrived to challenge the Palestinians for the honor of turning the camp over to the French.

The French reached for their weapons when one of the Lebanese whipped out a pistol, a Palestinian readied a grenade and young Palestinian guerrillas cocked their Kalashnikov rifles. Bloodshed was averted when U.S. Navy Lt. Conway Ziegler, 28, of Baltimore, intervened.

Ziegler, who speaks Arabic and French, is assigned to the unarmed United Nations observer team that has been here for years under a previous arrangement, and he came along yesterday to help the French newcomers find their way around.

He rode in the lead car when a French patrol set out to make contact with the Israelis occupying the villages just outside Tyre.

The patrol rolled unmolested down the main road linking Tyre with the Israel border - through scented orange groves and banana orchards where the unharvested fruit had been left to rot when its owners fled - and the patrol found the Israelis with their tanks fewer than five miles away.

The Israelis refused to talk to the French until the reporters and photographers who followed the patrol were sent away. Then they received the patrol commander, Capt. Jacques Neau, who said he was going to "tell them what I saw this morning in the city."

That cryptic comment was a reference to the crucial and very sensi-question that the French have to face here - the fact that Tyre and its environs to the north are under Palestinians military control. The Israelis want the Palestinians out, but it is not at all clear that the French U.N. team has the authority or the power to satisfy that demand, especially since the Palestinians seem to have survived the Israeli invasion of the south in good shape and are conspicuously displaying new weapons.

Salvan, the French commander, told some reporters that his mission was "to supervise the withdrawal of the Palestinians from the city." But he also said that "our mission is not to disarm or to block the movement of anyone."

Salvan's tropps face a problem that does not comfront the U.N. troops going into Israeli-held territory from the other side - that of conflicting and challenged jurisdictions that raise political issue if mishandled.

The government of Lebanon has had no authority over the south since the war, but is extremely sensitive to any suggestion that the de facto Palestinian jurisdiction is legitimate.

In the end yesterday, Salvan settled the dispute over control of the camp by allowing the Palestinians to stay and announcing that "everything is settled."

He then returned to Beirut to consult the Lebanese government.