Hi - fellow noob here and just getting into the forum.
I have done a lot of reading and watching and I believe you are allowed to sell copyrighted items as long as they are produced by an official producer or supplied by an official supplier.
I also believe there are not that many of those kind of items on Aliexpress though.
To avoid copyright infringement I think you need to find items that don't use the official logo or official copyrighted images etc. - and you can't call it by the official name if it isn't the official item.
For example you can't just call something "Marvel Thor's Hammer" when it's not an officially produced Thor hammer.
You can sell and describe things however like "Thor inspired Hammer - Just like in the Marvel movies" ... That kind of thing should keep you free of copyright worries. It would also help if you didn't put the Marvel or Thor logo in the pictures when it isn't - but you could "strongly hint".
If anyone else has any more info, or is able to tell me if I am wrong then that would be great.