Mason,
1st auction - In case of a tie, first bid wins. Had your snipe been a second or two earlier, you would have won.
2nd auction - You lost by less then an increment, which is a fairly difficult thing to understand about ebay. But, on the link about bid increments you’ll see, “Note: A bidder may be outbid by less than a full increment. This would happen if the winning bidder's maximum bid beats the second highest maximum by an amount less than the full increment.” Had your bid been $25.78, you would have won.
3rd auction – You lost by “AT LEAST” one bid increment. The winning bid was probably more then $51.
4th auction – You lost by “AT LEAST” one bid increment. The winning bid was probably more then $31.
In none of the auctions that you listed did you lose by more then 1 ebay increment.
The title you used for this thread was, “I must be sniper stupid!” Sniping is influencing nothing that has been discussed in this thread. Proxy bidding and increments are controlling the outcome. Had all the bids (including the snipes) been placed a day or several hours earlier, the results would have been the same.
I would still recommend that you read/study the link above about proxy bidding. Until you understand how that works, ebay will be a mystery.