The core idea of the root was:
the appearance, the likeness, similarity
On the German side, we have gleich (which includes a shortened ge-prefix) which is the word for similar, equal. And we have die Leiche, which means corps, but which originally simply meant someones appearance/body/likeness.
On the English side, the root is the origin of the word like – both the comparing-like and the verb to like, which might have gotten its meaning from a sense of feeling like something “suits” you, is “like” you.
The root is also the origin of the suffixes -ly and its German counterparts -(l)ich and -lig which originally expressed that something is “like” something. This sense is quite obscure in English now, but we can still see it in the word manly for instance, which means “like a man” – whatever that actually means :).