For other kingdoms like the ashanti and dahomey kingdom) there was always a paramount ruler. and tribal unity for the most partColonialism did set standards, for example the women had a political voice (in Igbo tribes) before colonialism occurred, once colonialism did occur the women were removed from the picture. There's an article written about it in which they talk about the process of "sitting on a man" and the results being Englishmen opening fire and killing 50 women because they didn't understand this form of protest, in which the women had been participating in before they had arrived. They actually figured the men had set them up to it.
They had rulers, but they also had systems that were set up that focused more on majority vote, like a parliament. When Europeans arrived, they figured that it was all based on one leader and a "chief" and so they elected chiefs and put them into place so that they could collect taxes.
Rule of law was there, but again, colonialism also enforced another rule of law. And I know they had their own religions, they also had Islam as well, and Christianity became a fact after the British came.
but yeah, if im not mistaken there wasnt really much of an Igbo Unity or identity until relatively recently which is probably why they were so easily penatrable thus being heavily affected during the slave trade. but I may be wrong about that. I the same could be said for the Ewe People.
and tribal identities (or klans) existed well before european contact.