I don't have an aviation background. What is the typical angle of
landing/approach for commercial airliners? There's an illusion for
novices, and it seems like the angle is much greater, even 30 degrees
or more, but I remember hearing it is much less, like under 10. At
what angle would the passengers complain of a rough landing.

ILS approach slopes are around 3 degrees, and I don't recall ever hearing of
any greater than 3.5 degrees or less than 2.5 degrees. I presume that PAPI,
and the earlier VASI, lighting systems conform to the same approach angle
that is (or would be) used for each runway. Instrument traffic and nearly
all multi-engine traffic uses the ILS and PAPI approach slope.

Single engine traffic, when using a power-off approach will typically have a
gliding approach between 5 degrees and 10 degrees depending upon wind and
flap setting. This is frequently done in training, and also as an expedited
arrival procedure, in addition to the obvious usefulness in the even of an
engine failure.

Credible, and occasionally impassioned, arguments have been advanced on all
sides regarding which is the correct normal procedure for single engine
aircraft under visual conditions...

Peter