Proofs that Jones polynomials are invariants of links:
The original one via von Neumann algebras by Jones.
An elementary proof by Kauffman.
Via Temperley-Leib algebras by Kauffman.
Quantum group representations by Reshetikhin & Turaev.
Several approaches in the HOMFLY paper.
Via Chern-Simons theory by Witten.
Khovanov homology.