Why do we use "-s" with verbs?

Question

Why do we use an "s" for some verb conjugations? e.g. *I run/He run**s***. Why can't it be *I run/He run*?

Answer 1

Sometimes the answer is: "That's just how it is"

English evolved from several other language families--each with its own rules and idiosyncrases.

You can trace certain things back to the source language, but others might be more difficult.

Use something like Google translate to explore the origin of different things you see in English.

For example, words of the form ____ing usually trace to the French ____ant form. eg portant in French is "carrying" in English.

Answer 2

The main thing that is good about your question is that you understand what the rule is and how to use it. very well. You also understand the difference in the use of present tense verbs between English and possibly your own native language. Unfortunately, rules of grammar are a little like many other things. We might not like that the sun rises in a predictable way, but there isn't much we can do about it. It just is what it is.