I need some theories to be cleared up

There was this theory where the time loop, if we take it to really exist, was somehow known by the monsters and they were just trying to stop Mono and Six to prevent perpetuate the cycle, but how would they know about the loop in the first place? Are we just going to assume they all remember the last loop and if we do then why do they still fail?

Another theory is that Six is just using Mono and is the reason why she sticked with him but his of no use anymore in the end that's why she dropped him. What is she using Mono for in the first place? If it is protection, them wouldn't it make more sense to pull him up so that Mono could still protect her?

And now that I think about it, how do we know that time is really faster inside the tower? We only saw the thin man grow but didn't see the outside to say this and we know that the thin man gets back to the past which is why he encountered young Six and himself. Maybe Monster Six being huge could be because of the music box or some sort of magic because she reverted back to being a kid again when the music box was destroyed.

TYIA for answering and if you don't believe these theories then you could also share your thoughts on how these could be acceptable theories.