You should read Rethinking the Chess Pieces by Andy Soltis. Piece values have been quite variable over the past three centuries and even today.
mathematics of relative chess piece value
Table 6 https://arxiv.org/pdf/2009.04374.pdf
N = 3.05 P, B = 3.33 P, R = 5.63 P, Q = 9.5 P

Table 6 https://arxiv.org/pdf/2009.04374.pdf
N = 3.05 P, B = 3.33 P, R = 5.63 P, Q = 9.5 P
I haven't read it yet, thanks.
I do not think the rook is strong enough to be given a 5, rather a 4.5. The bishop is geometrically similar to the rook so its value should be the same, minus a point to compensate for the position, so 3.5. The knight is a short range piece that is vulnerable to any point blank attack, yet it can move with an L shape over and around pieces. I give the knight a 3 to compensate for the weakness to the rook and bishop.
Knights are better than Bishops in certain positions. This is why they are both 3. Bishop's biggest weakness is only being able to touch half the squares on the board, which is why the Bishop pair adds to their values. Knight pair isn't as valuable, but is still a strong duo. Knights biggest strength is being able to move through closed positions.