The wiki article include descriptions of several visits where they seem to understand gift giving as good will quite well:
> During a 4 January 1991 visit, the Sentinelese approached the party without weaponry for the first time. They collected coconuts that were offered but retreated to the shore as the team gestured for them to come closer. The team returned to the main ship, MV Tarmugli. It returned to the island in the afternoon to find at least two dozen Sentinelese on the shoreline, one of whom pointed a bow and arrow at the party. Once a woman pushed the arrow down, the man buried his weapons in the beach and the Sentinelese approached quite close to the dinghies for the first time. The Director of Tribal Welfare distributed five bags of coconuts hand-to-hand.
But even if they didn't, it's quite possible that there are other factors influencing their decisions than basing it purely on receiving gifts. As for the missionary that was killed, it seems disliking proselytizers turning up at your door is another universal human attribute.
> During a 4 January 1991 visit, the Sentinelese approached the party without weaponry for the first time. They collected coconuts that were offered but retreated to the shore as the team gestured for them to come closer. The team returned to the main ship, MV Tarmugli. It returned to the island in the afternoon to find at least two dozen Sentinelese on the shoreline, one of whom pointed a bow and arrow at the party. Once a woman pushed the arrow down, the man buried his weapons in the beach and the Sentinelese approached quite close to the dinghies for the first time. The Director of Tribal Welfare distributed five bags of coconuts hand-to-hand.
But even if they didn't, it's quite possible that there are other factors influencing their decisions than basing it purely on receiving gifts. As for the missionary that was killed, it seems disliking proselytizers turning up at your door is another universal human attribute.