This package has tons of characters that look different and can be quest givers:
The same developer has a few other packs of many-characters; “street wear” and “female” and “swimsuit” variants.
If the art style isn’t what you need, then you’re running into the problem that any game cobbled together from the marketplace won’t have a unified art style. Them’s the breaks.
If you need fantasy theme, you could buy a bunch of the “hero” and “archer” and “swordsman” and even “skeleton” and “vampire” characters and place them around your level.
If you feel really frisky, you can even change their hair and clothing color pretty easily with material swaps.
The next option to get variety is to use something like MakeHuman. You can create characters there, export to blender, and then export to Unreal in turn. Browse around here for some options: Fashion | www.makehumancommunity.org
If that somehow still isn’t good enough, then what is good enough? Maybe what you really want is the kind of modular, pluggable, standard, with many different assets, that I’ve described above. That’d be great, but we don’t have it. Building that kind of system is not realistic for an indie developer without a few hundred thousand dollars to spend on outsourcing, or a year-plus to spend on learning character modeling.