I took a few hours and did some more in-depth side by side comparisons based upon what I initially posted.
While I stand by my initial posting (and clarify that my language was purposefully opinion-based), I wanted to further expand upon my new findings.
-The various necklace designs appear similar to those found in other retro games; my intial impressions about similarity to certain GameBoy game sprites was indeed correct.
-Bow and Arrow is not a direct 1:1 rip from LttP like I initially thought, but it is similar enough with very minute variations as to copy the 'look and feel' of said item in said game.
-The hooked staff from FF1 and the potions in general. All have been (slightly) modified to avoid direct infringement but it still is far too close IMHO.
-I double checked the Strider boots and it is no wonder I was calling it a direct sprite rip. Jeez. The 'Strider' NES style of spritework is unique among the field of NES 8-bit spritework and while the asset-based boots on offer here are not 1:1 copies, they are DAMN close, even so far as to have the unique buckle on the base and the curve on the 'top' of the boot. The slant of the screenshot makes it difficult to do a precise comparison at this time.
-For everything else, I have compared them to both NES and gameboy sprites and found very striking similarities to existing artwork from older games.
TLDR: I haven't found direct 1:1 rips from older retro game sprites at this time. I would still caution against any developer considering obtaining this 'asset pack' for their own games because the striking similarities to older titles is far too close and may be seen as too derivative/cloneish. There's a fine line between homage and outright plagiarism. I'll give the asset pack seller the benefit of the doubt and presume they are on the homage side of things.