Why X-Men series Story doesn't add up, No Continuation?

[Swordnen]

• When they were old Mystic was alive but in dark phoenix she is dead.
• In wolverine 2 the Japanese guy cuts his adamantium claws, and he grows bones, but in days of future past he has metal claws.
• If Deadpool was at the time of early x-men, why he didn't come for help early?

I have watched up to Dark Phoenix. So no spoilers!!!

Updates

+1 y

One point left-
- In logan why there were poor? Why they were in living hell?

[boggboss]

Because some are not direct sequels pretty sure there are vids online that will explain the order and if they are in the same universe