Let's say nobody died, it wasn't a massacre.

No one is saying no one died (though no one died in the square, which is helpful for spotting when someone is lying)

Those are all flattened bicycles and scared people on the ground.

Yeah, that's what's in the one picture

This is still the state sending the military to put down a protest.

The protest had been going on for weeks right on the equivalent of Pennsylvania Avenue in front of the WH and, critically, a couple of unarmed PLA soldiers were burned alive by incendiaries and had their corpses strung up in the open. Some people also stole some guns from inside an APC that got burned (though I think that fire was an accident).

Most protestors left well before the tanks got there because they listened when the state said "disperse by this deadline". One of the big holdovers besides militants was from people following the leadership that was deliberately trying to instigate bloodshed so they'd have propaganda to exploit (and they said as much in private beforehand!).

Those are tanks from the national government

The entity centered a stone's throw from the Square, yes

directed at unarmed young adults from the same country right?

Afaik the tanks never fired and they and the other military elements weren't there to attack protestors. In the Square itself, the highest level of violence was hitting some people with batons to get them to leave. As far as I know, there were no major physical injuries from this. The lethal violence was between soldiers and militants elsewhere.

What would've happened had people not dispersed?

Soldiers would have kept getting killed and there probably would have been an attack on the federal buildings right nearby.

Were the tanks and guns just to scare people?

The tanks? Yeah, they wouldn't even be very useful against the militants unless the CPC wanted to knock down some buildings (which they did not). The guns were mostly for intimidation but also to kill militants who fought the force sent to disperse people.

What would you think of Biden or Trump calling our military to put down protests like what happened in summer of 2020 in the U.S.?

Considering the level of militarized violence used against protestors who killed zero people and the fact that one dude who shot someone in self-defense was literally black-bagged on the President's direct orders, to say nothing of the many organizers who were killed deliberately outside of the protests and were written off as "suicides" with no note or history of depression . . . I don't see what you're trying to say.