Bad news: we lock people up without trials all the time, for lots of reasons that have nothing to do with homelessness.

In the United States, all crime is like that. Areas with no cash bond are better about it, but most places only let the people before trial out if they can afford to pay.

If homelessness is illegal, are homes being provided? How are homeless people supposed to just manifest a home out of the ether?

What my city do is issuing a ticket. At some point some people have so much tickets that it dosen’t matter if they get out of their situation or not

i dont know where OP was going with this. but..
the criminalization/coercion of street-homeless to overcrowded sub-standard shelter.. basically is a prison( remarkably similar to jail) or concentration camp.
a significant chunk of the residents are ex-cons who recently got released but they dont have money+job for an apartment(if they even want one).

making homelessness illegal

That's a great idea! Other great ideas:

• Being poor is a lighter offense, poor people should get fines
• But you should face a death penalty for suicide!
• ...Actually let's delegalise all forms of dying.

The devil is in the details. You have to define homelessness first. Would a ban on that even be legal? And what is the state doing to prevent it and/or what are the penalties for violators? There is certainly a chance that this inches painfully close to keeping people concentrated, in a camp, which should, in a sane world, weigh heavily against such a ban. But if a ban meant anybody on the street gets put in an apartment, given medical care including therapy, and then given a chance to become a productive member of society within their means, then it wouldn't be imprisonment. That's the Finnish solution to the problem, which benefits from having a smaller population in the country overall and a smaller percentage of homeless people than, say, Los Angeles.

I'm not following your logic on this one. I mean, we are definitely shit to homeless people, but I'm not seeing the direct logical connection you're making cause and effect wise.