Mark 16:9 to 20 does not appear in the early manuscript evidence or early Church fathers. It was likely added because the ending appeared to be so abrupt without it. There may have been another ending that we are not aware of but, in truth, the Holy Spirit rules. The other gospels fill in the blanks.
One thing that goes away when this is no longer included is snake handling. I don’t think that’s a bad thing.
You are quite wrong here.
Mark 16:9-20 were certainly there.
Tell me more about what you think you know about “early manuscript evidence” and to which “early church fathers” you refer.