Autism

Well we know how they lived and their culture (as always it depends on the region), how they dressed.

Religion wise, we know they had similar gods to to the norse/north germanics (skandinavia. You know thor, odin, frija, loki aso). They put people into the swamp. Criminals and religiouse human saceafises. We know that its religiouse human sacrafises because there are also animals and tools found in swamp beds.

Burrials and funerals were different to each region and tribe. Many in the south and north west burried their people in hills, like the celts. The bodies sometimes were put in specific positions. As the romans arrived, these practises noticeablely changed. Building dedicated buildings, giving offerings and money. From what i have also read is that cremetion and burning the body was also a common practise.

But how they really worshipped, and their mythologie we have nothing on as faar as i know.

Idk if that is true but i think we also know that they, also had some spiritual leaders. Oracles. Young virgin woman that could predict the future threw bones, weather speak to the gods and stuff, that had a set place where they lived and rulers traveled to them.

Things are waaayyy worse with the celts though. We know they had these druids. But we do not know what their job in society was. We guess they were spiritual leaders, maybe also medical, maybe diplomatic. The druids were not just a closed off people. Didnt write anything down themself, the forest was holy and no one but druids was allowed to be at their meetings and in their forrest.