The 16 cups are valve seals, I seem to recall you bought new heads, those are part of the heads...
The two rubber L shaped parts are inserts for some rear main self, most engines don't use them...
The O rings are for the distributor & the oil pump... Not all distributors have a groove for the O ring & the oil pump you probably put a new oil pump on which would have that O ring already inside..
The two white rings & the two gaskets with a teardrop shape & two holes are for Air Injection (smog pump) you don't need them
The gasket above is a thermostat gasket for a motorhome...
The big circles are carb to air cleaner use the one that fits...