Is there a word or term commonly used to describe the act of stating the obvious (or a person who continually does so)?
He constantly states the obvious, he is such a __.
She is always ___ing.
As a somewhat insulting noun, "Captain obvious" can be used for someone who is always stating the obvious.
Prolixity can be used to describe someone who says too much. This may be applicable in some cases.
In addition, Logorrhoea is a term with a similar meaning to prolixity although again the primary meaning is simply too much vs. stating the obvious.
I don't believe there's a single word that has the exact meaning you want, but the phrase "belaboring the obvious" is a classic idiom for your second case.
Stating the obvious is perhaps best stated as "self-evident." For example, "A street is better than a little trail to connect those two large neighborhoods." "That's self-evident."
Redundant is the word that you're looking for, according to Merriam-Webster.
So you can say:
Please could you be less redundant and get straight to the point?
I believe you're looking for belabor, which means to redundantly or excessively state the obvious.
I think a bromide would be apt for your query.
Instead of offering an umbrella to her, the cheeky stranger offered the bromide: "It's raining", much to her dismay.
Platitude, as in "He is full of platitudes"?