MicrostockGroup

Interesting question. To short the things, you may want to shorten/enlarge the graphic by 1 pixel in any direction. The result will be automatically something else.
Comparing pixel-by-pixel an image and finding similar, means, by default, derivative work. Regardless who owns the copyright of the original image (except author died 70 years ago (in several countries 80 or 90)).
For those, vectorized and enlarged images of pixels, it depends. If Bill Gates is complaining, you've lost. If me, you may win... (But don't wait too much!)

In the reality I prefer to derivate work from something free/open source and forget the commercial resources...

But in this case, if you are going to draw a small arrow with pixels and it needs to look like a computer arrow, there isn't an endless amount of ways doing it.

In this case you shouldn't use any 16x16 or 32x32px cursors or other icons. Anybody can find easily any similarity, even if you had completely redrawn the image.

Just being an ass (that's directed at myself...)

I doubt if an arrow can be copyrighted, just like Arial Black, Gothic, Courier... and many common fonts that pre-date computers (but not including the creative new scalable fonts that someone has designed). Here's the main point... Bare facts are in the public domain. Works must show sufficient human creativity to be eligible to copyright at all. Mouse arrow is like, square, circle, rectangle Etc. too simple to be protected.

This also relates to PD images that some people want to shoot or scan and sell on Microstock. Well fine, but if there's no creative alteration, it's PD so anyone can borrow it and use it free. Thank you for your time digitizing it for them. Copying images from NASA or some other US agency, they are PD (except when they contain humans or copyrighted materials) but starts, desert photos, those things are PD. And unless they are changed in some manner, they can't be protected as just being a copy. Heck some people were as bold as download,  maybe rename and then upload. Talk about lazy! Small wonder the agencies have stopped taking most of that.

Personally I'd like to copyright the letter W, it's not used that much and for a small fee I could protect it and defend my ownership.