Aragorn was descended from Elros who was a half-elf, but that was so long ago he may or may not be a full man depending on how racist one is about miscegenation.
Legolas was an elf and Gimli was a dwarf, so explicitly not Men.
Elros and Elrond had a choice as to become Eldar or Edain. Elrond chose Eldar, while Elros chose Edain. Once they chose their mixed nature was resolved.
Not exactly, since the Númenóreans still had longer lives than Men due to their elven heritage. So while one could absolutely make the argument they were Men, there's also a case to be made saying they weren't pureblooded Men.
The Fellowship broke apart because it wasn’t strong enough to make the journey. It never was. Bormir is the reason that the Ringbearer was able to make it away from the Fellowship’s camp and eventually to Mordor.
I didn't say he wasn't. I don't fault him for it; no one could resist the power the Ring promised forever. But it's a fact that his moment of weakness is what caused the party to split; because that's exactly what happened.