Q1)
A. We all have a nose.
B. We all have noses.
Are they both equally fine?
Q2) When each of us has a bag and the bags are of the same kind,
A. We all have the same bag.
B. We all have the same bags.
Are they both fine?
Thank you.
Q1)
A. We all have a nose.
B. We all have noses.
Are they both equally fine?
Q2) When each of us has a bag and the bags are of the same kind,
A. We all have the same bag.
B. We all have the same bags.
Are they both fine?
Thank you.
The expression "We all have a/an…” is very common in English, for example:
We all have a story / a threshold / a vested interest
We all have a past / a dark side / a cross to bear
We all have a role / a responsibility
We all have an ego / an iPhone / an idea etc.
I'd prefer the singular "a nose" but everyone would understand (b) "We all have noses" because our life experience tells us that humans don't have two or more noses. A less ambiguous statement would be
However the OP's second example, "We all have the same bags", needs clarification because it could suggest that each person is carrying two or more bags that are identical.