The Villans led 2-1 heading into the final minute of play at Vicarage Road on Saturday, but Aly Cissokho's red card proved costly as Birmingham City fan Troy Deeney struck twice late on for the hosts to seal a 3-2 win.
It was a cruel blow for Villa who looked comfortable for much of the afternoon, but Black believes that there are still plenty of positives to take from the match - including the spirit shown by his squad.
Speaking to reporters after the game, the stand-in boss said: "The players have been criticised, and justifiably so, but not today. Ultimately of course you need to win games but there was a lot to be encouraged by.
"It's a fantastic football club with fantastic supporters and maybe it's just one little step towards getting the supporters back on side. I thought the effort of the players was outstanding.
"They showed desire and hunger but the sending-off changes the whole context of the game. At 2-1 up, I thought we looked like the team who were going to score again. The key moment is the sending-off."
Villa's relegation to the Championship has already been confirmed, with just three wins to their name all season in the top flight.