I am thinking of having a language in which writing is based off of the Arabic script except full on letters are added for vowels that in Arabic are just represented by dots and their position and number. At the same time I was thinking of having the grammar be not all that similar to English or Arabic(some similarity like with double negatives, I will accept but I want to limit this grammatical similarity).

I just think that if I make a conlang with the Arabic script and Arabic grammar that I would really just be inventing a dialect of Arabic and not a conlang whereas if I go the other direction and try to make it as similar to English as possible, I will get English with a weird writing system.

Now I am not sure I would want genders and cases and conjugations and declensions.

I mean yes if you take a verb in English and inflect it, you get conjugations but those are not conjugations from grammatical case+gender like in say, Latin. Same with inflections of nouns and adjectives in English being declensions but not from grammatical case+gender. Arabic has gender and case so this would be a place where more English similarity would be desired.

I mean with gender, how do you decide which words are neuter, which ones are masculine, and which ones are feminine when most do not have to do with the biological sex being known or unknown.

For example, it makes sense that these words translated into a conlang would be feminine:
Beauty
Pregnant
Milk
Breast
Garden(my fictional world has way more female gardeners than male gardeners)
etc.

And it makes sense that these would be masculine words:
Muscle
Strength
Hunting(my fictional world has way more male hunters than female hunters)
etc.

And that these would be neuter words:
Baby
Infant
Toddler
Neutral
etc.

That last list is mainly because in my fictional world, there is domination of 1 fictional species and that species happens to be externally gender neutral but internally obvious until 5 years after birth when it becomes obvious externally.

Anyway back to grammar, most words do not have to do with children or age or females or males. But with gender they can't all be neuter otherwise gender would comprise a minority of words as far as grammar. But with something like chair or computer or yarn, how would you decide the gender? Statistics(like for example how many females knit compared to males)? Randomness?

Similar logic goes for grammatical case.

And what about verb tense? How would I decide if I want it to be tenseless with time expressions used next to the verb, past vs non-past, future vs non-future, past, present, and future, or multiple degrees of past and/or future depending on the time scale?