To work on most American vessels you would need to complete your STCW training in the USA. Your foreign STCW won’t be accepted. Most (but not all) seagoing positions require MMC.
Your Mexican MMC is invalid on American vessels.
You say you are a deck cadet, but don’t say whether as officer or unlicensed. Officers on American ships must be American citizens
You can sail as an A.B. seaman but you need an American A.B. endorsement. Your foreign seatime, if any, may count as part of that seatime. You apply through the USCG for the endorsement/ MMC.
You can sail as OS/wiper without an endorsement, but for many positions you will still need the American STCW training, and the MMC.
American fishing vessels, and some American vessels operating wholly in U.S. waters, don’t require any STCW endorsement, but still need endorsement for the A.B. position, and officers must still be American citizens. OS/wipers don’t need MMC on fishing vessels.