I disagree with the people saying that your MC has no voice. He clearly has one. It's just extremely dorky and not the typical go-get'em MC that's in a traditional story. However, it is the sort typical in an isekai story like this.
Also, monologue heavy is fine for stories of this type.
I guess the major things to keep in mind for your rewrite are whether you want to be closer to what people would read in a translated isekai light novel, or if you want it closer to traditional fiction.
Right now, I'd say your story is a pretty decent isekai novel. It's better than most things that I've found on novelupdates in the past when digging through the pile for more isekais to read.
The primary thing that I would change in your story is probably just some grammar and tense parsing as well as reworking the intro chapter into first person to keep it like that all the way through. After that, I'd probably do some reparagraphing to have information strictly about the MC in one paragraph and splitting up external information in other ones to help with the flow.
As for things to work on, you've mentioned it already, but you could improve on your descriptions. It's kind of hard for me to put my finger on what exactly's off with it... but I think it's something like you're emphasizing the wrong parts and not emphasizing enough the main parts?
In short, I don't think the story needs a rewrite. It just needs some TLC to get rid of awkward sentence structuring and tenses, as well as a bit more fleshing out of descriptions.
After all, the premise of your story is a guy being reincarnated as a snake, and not an OP one. What we got is a discovery channel-esque adventure of a snake in his daily life, slowly getting stronger and growing up. I'd say that's a decent selling point there.
It's definitely not a grandspanning action adventure isekai novel though. If that's what you had in mind, you definitely failed on that part. But as the story stands, an easy-going story about a snake and his snake family living their lives, I think it's pretty good.
This has been your local happy and vain writer.