There is an absolute rule that copyright does NOT cover type fonts, and that rule has been extended even to unique typographical designs. Also, simple symbols and common geometric shapes generally do not qualify for copyright protection. So if your logo is made solely of type, or a relatively simple graphic shape, the copyright analysis will not apply.

With respect to pictorial or design elements, copyright covers “expression,” that is, the artistic choices made in expressing an idea, but not the underlying idea itself. For example, more than one illustrator has depicted the idea of a figure removing part of his head along with his hat. However, there is no infringement when the artistic decisions used to depict that idea are different, e.g., different postures for the figure, different composition, and different rendering styles.

Technically, I guess one could make the argument that Elly Bellys head is copyright infringement, because of it's similarities to an emoji. It's a Yellow head.

Copyright infringement occurs when your new work incorporates artistic expression from the original, even if it takes only a small part of the original work, and even if you add a lot of your own original expression.