[Campion]

Ad populum was there originally (in fact, it was there in some places well before the Novus Ordo) in places with freestanding altars. Lay readers were also there from the beginning, and (IIRC) from sometime before that.

(Recall that we didn't go straight from the 1962 TLM to the Novus Ordo; there were several transitional stages beginning in 1964. (Somewhere I have my First Communion missal from 1968; the 1968 Mass was basically the TLM, somewhat simplified, in English. The major change when the NO was introduced the next year was much more simplification / abbreviation, and 4 Eucharistic prayers instead of one.)

The rest of the stuff you mention are all later additions/innovations.

[ebb tide]

I never witnessed lay readers, nor ad populum, in the U.S until the early ‘70s.

I don’t know where you witnessed them. Europe, maybe?