my images rejected

Ink blots and hatch marks are easy to create in Photoshop or Illustrator. I don't need to pay for them.

I think you'll need to step up the sophistication & quality of your artwork to be accepted into Stock inventory. The competition from other talented Contributors is quite high. See links below. 

https://stock.adobe.com/search?k=hatch

https://stock.adobe.com/search?k=ink+blots

Quality is not a matter of resolution and the ppi (not dpi) value is irrelevant. 

You first: you need to crop that more narrowly. It does not make sense to have a huge image with a lot of nothing on it. They may think that the cutout is not good enough. 

Your second: same cropping issue, but not that strong. Here, I would guess that the main issue is the cut-out work.

As for the third picture, I do not see a direct issue, but an issue with the usability, which would be a different refusal. 

It may well be, that Adobe considers this not to be usefull in their database and that the moderator just erred in the reason, as they should have selected the AESTHETIC OR COMMERCIAL APPEAL OF IMAGE refusal.

Size and PPI are not issues with respect to quality. The majority of buyers of Adobe Stock are graphic designers themselves and would have relatively few problems designing such assets themselves. That said, ink blotches of this sort are in fact available on Adobe Stock, but they are often submitted as sets of a dozen or more in a single asset with variations to each. Why use credits for a single asset when sets of multiples are available for the same cost?

I don't know what kind of demand this artwork has, or how much like it already exists, but in my opinion it has a lot of usage... if people can find it.

You have a problem with consistency, image 4 looks blurry in photoshop, unlike image 3 that looks better. Image 5 is a png but it's not separated from the background, why? this forces a buyer to only use in a white background. I would also consider doing more versions with colors, like I said I see lots of ways designers can use in their art work.

Adobe is less interested in artwork and more interested in sharp, crisp images. Your images are fuzzy when viewed at 200%.