No less an authority than Chuck Berry defined Rock music as having a back beat (you can't lose it). Nearly all Rock is 4/4 with a back beat, although there are a few songs that stray from that. Blues differs in that it doesn't necessarily have a back beat and isn't necessarily 4/4.   ("To bring the funk you gotta beat on the one" attributed to James Brown.) ( "I put a Spell on You"... one two three... one two three... bump... Screamin' Jay Hawkins.)

I play a lot of tunes that are 2/4 or cut time. I also play 3/4 and 6/8 stuff that is definitely not Rock. Bluegrass breakdowns (which I don't play) are, I am told, 3/4 pieces sped up to 2/4. As an American old time (sort of) banjo player, I syncopate most of my tunes. I really enjoy listening to unsyncopated folk singing, especially that sung unaccompanied. I am bored to death with constant 4/4 with a back beat, but many younger musicians can't seem to wean themselves off it. (Celtic groups are not part of the discussion in my post as I am only dealing with my own musical heritage and I'm not Celtic.)

That being said, I never tell people what to play at jams or make a fuss after the fact over musical styles. I'm just happy to see someone giving it a try.