How does the copyright law protect original characters?
It is true that ideas or concepts cannot be copyrighted and that is precisely the reason why you need to illustrate it and describe your character’s unique powers or abilities into writing. Copyright takes effect at the very moment you created it. You don’t need to license it. But publication is a requirement since it is your evidence that you have created it. Post your drawing anywhere that is public or viewable by the public. A public FB post is enough for the publication requirement since it has a non-tamperable date. Date of creation is important in case of conflicting claims. You can also share it in group pages like this.
Other writers and artists infer that concepts or ideas can’t be copyrighted because they saw Marvel and DC have similar characters. But actually, if you look closely at those characters, it’s either they have generic and or public domain abilities or the DC character, even if a rip-off, didn’t really copied the unique ability (the one protected by copyright law) of the Marvel character or vice versa.
Let’s take one example. There are many Captain America-like characters that were created by DC and other creators. They also have shields (wielding a shield is a public domain ability), some are circular others are not. But none of these characters’ shields can be thrown and return back. There’s a court battle between Marvel and another creator. The judge ruled that the creator can retain his Captain America-like character but he can’t throw his shield because this concept (ability) is unique to Marvel’s Captain America.
Finally, if you can see a Captain America-like character who can throw his/her shield and the shield can also return, check it again since, for sure, it is also a Marvel character. Part of the right of the copyright owner of a character is that he can copy his own creation or make derivatives out of it.
There are spiderman rip-offs but none really webs like the way Spiderman do it. It is copyrighted. Another is Batman. You can have a genuis, detective, and ninja-like character who also have grappling guns but he cannot throw a bat-shaped shuriken and can’t have a bat-shaped cape.
Instead of copying an original character or its abilities, which is illegal, ask the original creator whether he can allow you to use his character for free in your comics. Most likely, he will since he’s also interested with the free promotion your comics can give to his character. Both of you can also agree on some little modifications on the design and backstory you can make to the character.
Adding awesome characters created by others can make your comics more interesting and, hence, increase your sales. At the same time, it will also promote the said characters. So, the benefit is mutual.