‘ir’ verbs will transform to end in ‘e’ instead of ‘i’. Why?

So we have 'to' form verbs, right? And they end with 'ar', 'er', or 'ir'. When we want to change that verb to 'he/she + verb' we remove that 'r'. For example the word 'hablar' to make it 'he speaks' you can just say ' habla' and another is 'hacer' but this time ending with 'er'. It will become 'hace' if we want to say he/she speaks. But it is kinda different with 'ir' verbs. For example 'venir' will become 'viene' instead of 'veni'

edit: I know it's kinda stupid to ask why because it sounds like I'm asking "why spanish is like that?" but actually what I mean is "why ir verbs different from ar and er."