Rivers of ink have flowed over the grandfather's paradox, many "trying to demonstrate" at the conceptual level the impossibility of time travel, others have managed to avoid that limitation using the idea of parallel universes. But let's not fool ourselves! the real paradoxes are found in the future or rather in the future if we could observe it.
Why do I say this?
We can do a mental exercise to understand why.
We have the technology to see through a screen what it will contain ten minutes after the current moment. If this were so we would find that depending on what we can see we could create a paradox or not. why?
If what we are seeing is foreign and distant to us and if we do not perform any action to change it, nothing could possibly happen, everything would happen the same as we have seen it, but the thing changes if we are seeing ourselves as in that case they can happen two things: we do not do what we have seen and this will make "that universe-reality" never exist from our point of view or we try to reproduce the same thing that we have seen ourselves do something that is impossible for us to reproduce as much as we try and which would also lead us to "that universe-reality" never exist either.
We can try it! If we videotaped ourselves and then tried to reproduce exactly all our movements, even if we tried a million times we would not succeed.
So if we could see the future the same act of seeing it would be changing it.