I believe most of the noise I have
encountered with engines at startup ... noise ... associated with hydraulic
lifters pumping up

you can hear that alright, but listen to the other clattering going on. It is
pretty serious noise.

If one has a hard time recognizing the sounds of pressure oil bearings working
without pressure oil to them, start your engine right off, listening to the
sounds coming out, taking care to hear the change in sounds over the next ten
to sixty seconds (much quieter), let the engine run a couple minutes and shut
off. Then restart and notice the difference in sounds.