I noticed that the nous form of verbs always ends in -ons. For example, nous allons/allions/irons/allions/allassions/irions. However, the passé simple tense of verbs seems to always end in -mes (with the previous letter being a vowel with a circumflex).
Why is there this inconsistency? Is it because passé simple is a literary tense and "hasn't evolved" for some time? At least to me, it looks closer to Latin -mus than the other ending.