The specific image is a variation of a generic icon.
You are clearly inspired by the artwork. The moment you decide to create your own artwork will determine if it is a copy or the result of the direction your inspiration takes you.
For example: The artwork of a weight lifter can inspire an image of a flexed bicep, say.
Suppose that your inspiration from the artwork takes you to a modelling agency where you hire a weight lifter type and props; photograph the silhouette in a photographers studio; and convert the actual image into vector art using conventional software, say.
Suppose, for argument sake, I scan the ShutterStock image but add boxer shorts rather than form-fitting briefs. And Save As mine.
Both are nearly identical to the ShutterStock image.
Both are copies. Perhaps not identical copies; but, copies nevertheless. For that matter, even a poorly hand-drawn, and crude image can be said to be a copy if intended to be similar to and used in a manner to imply the copy is representative of the original. Both try to circumvent (infringe) the rights of the creator of the original work. The term plagiarized can be better used in many cases.
How much different must artwork be to be yours?
Your best option is to make your artwork different with a small but distinctive detail that might otherwise escape notice.
Map makers would sometimes add an alley or natural artifact to identify their intellectual property.
In the above weight lifter artwork, for example, I made the bar thinner in the centre than the ends.
No one would notice that detail and I could use it to identify my work easily. I would wait to disclose that detail in litigation to prove my case.
