I am a new graphics designer I want to use skull head, spoon icon, fork, etc in my logo from free stock but I don't know how to avoid copyright issue
Simple answer: don't use other's work in any logo you design - yours or a client's.
That will avoid any copyright issue.
However, also bear in mind that a "derivative' work, at least here in the US (and I believe in UK & EU, but others will have to verify) doesn't have to start with a literal copy: if you copy the design intent, the idea, the visual concept, and execute it yourself, you can still be at legal risk.
Put it another way away from the legal nonsense - why would you want to use someone else's work for your logo as a designer anyway?