Yep, a personal is a foul against a player, i.e., a person (thus, “personal”), not a ‘procedural’ foul (offside, false start, etc.), or any other foul that does not involve contact between players (illegal passes, batting, kicking, UNS, etc.). Holding and illegal blocks in the back certainly involve player-to-player contact, but do not inherently involve player safety, so, those are not ‘major’ fouls. They were, at one time, but were reduced to 10-yard distance penalties to distinguish them from major (Personal) fouls.
For a very long time, we did not signal or announce ‘Personal Foul’ for many fouls that had their own signal (facemask, roughing the passer, roughing the kicker, etc.). But, for the very reason we identify these fouls as personal fouls, i.e., player safety, the powers that be asked us to use the personal foul signal for most (if not all) player safety fouls.