Anthony Elanga and substitute Joe Willock had twice put Newcastle ahead before Dominik Szoboszlai's 96th-minute penalty, awarded after Lewis Hall's foul on VĂctor Muñoz, salvaged a point for Andoni Iraola's Liverpool on an emotional afternoon that saw both sets of supporters pay tribute to club great Kevin Keegan.
Jaissle, picking up his first point in charge, felt his young side deserved more.
"In the end, I am a bit disappointed. We were so close to getting the three points, for sure. But there is also some brightness, definitely, because the guys were doing an amazing job for over 90 minutes. We are a young squad and they really left their heart on the pitch and this is something we can build on."
On the penalty itself, he was blunt.
"If you give it, it's a really, really soft one and then you have to give many, many penalties throughout the game and throughout the season. I'm not a big fan of the decision."
The German was encouraged by how his side executed his approach after less than three weeks in charge.
"I'm proud, we are proud to see a unit on the pitch. The guys were trying to do it the intense way that we wanted to play. Front-footed, vertical in our approach. This, after such a short amount of time, I'm really happy. We have a clear idea of how we want to play football and today we saw quite a lot of that."
He also praised the atmosphere generated by supporters.
"I saw the young lads fighting for everything. There was commitment. A good synergy with the fans. This is special, it's going to be a really cool season with big challenges as well. Amazing. Pure happiness and brightness. I heard many things but I felt the goosebumps straight away. You get energy from the stands and you just want to deliver it on the pitch."
Andoni Iraola, speaking to BBC Radio 5 Live, admitted the result flattered his side.
"Difficult to express the feeling. It's probably not the result you want when you come in before the game but we definitely deserve this point and even more. The team has never given up and we've recovered one point and probably the taste is better because we score in the last minute."
The Spaniard broke down both goals conceded.
"Both goals are very similar, probably different reasons. First one we have a great chance to finish. I think Ryan is on the edge of the opposition box and it's a clear corridor to finish. We don't finish it and then they punish us. Great run from Elanga, incredible. And the second one I think we have the numbers to defend better. We probably should have closed it before but also give credit to them."
Despite the goals conceded, Iraola took heart from his side's overall showing.
"I've liked a lot of the things I've seen from the team today. Definitely things to improve like the goals but I've seen a lot of things I've liked from the team. I've liked the energy, especially the players coming from the bench."
On the Kevin Keegan tribute, he added: "It was probably the best fixture to happen for the first game of the season after what happened. It's good that both supporters can remember him like they did today."