Maybe you found a quarry or manufacturing site with all those flakes , nice point in pic 9 also looks like possibly a small triangle point in the group pic I circled the one that looks like it may be
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the yellowish stemmed point would be a perkiomen broad point see this link Perkiomen Projectile Point whole ones go for a decent amount especially jasper ones, yours looks like the tip got knocked off. they are usually pretty thin so a whole one can be a challenge to find.
hole in rock is from erosion. But if it was found in the same spot as the rest who knows--could have served a purpose.
I will have to take a separate pic of the smaller one you circled. What part of the shore are you? I used to live outside of Cambridge.