Zombies come in a few flavors and they all love to collect shiny things:
The regulars, They're weak (Like, fogmen weak) And unarmed. They attack in great numbers and their race has 3 added to their global attack slots.
The brutes: See the regulars, except high martial arts and weather immune with lots of health. They are uncommon except in acid biomes and mega hordes.
Human infected: They equip what they can find and generally follow hordes.
Intelligent Infected: The leaders, they craft their own katana's and can use ranged weapons. Beware, I set them too powerful, one took out the town of Shark. They accompany mega hordes. Don't forget to loot them for organs and blood, cure research materials are valuable to the remaining scientists of the land.
Hulks: Extremely powerful with a lot of health but about as slow as something in Kenshi can be. Best to use crossbows against this. These guys can be found in unpopulated areas.
Runners: Now I don't like Runners either, but something like this was needed. They're very weak with low health but are very fast. They aren't very common either. You could expect a few in large groups
Stalkers: A much faster version of Brutes, long-range scouts for the Infected. They are not seen very often or in great numbers but can accompany small groups of Infected to offer support.
Also expect assaults on your towns as they grow to reasonable sizes. You might find it challenging to build anything substantial. I'm sure you can find the source of the zombies in a remote location and stop their assaults once and for all.
Finally you can now craft and cook zombie body parts into useful items with the right research and time. It makes all that killing worth your time