The West Ham United defender, on loan from Arsenal, scored England’s second goal in a 3-1 win over Portugal at Turf Moor on Thursday night.
And the 22-year-old says that the spirit and belief in Gareth Southgate’s squad is something he hasn’t experienced so far in his England career, which has seen him capped at senior and U17 level previously.
France U21s v England U21s
International Match
8pm, Monday 17 November 2014
Stade Francis-Le Ble, Brest
Live on BT Sport
"We’ve got a fantastic team here and there is a lot of belief," said Jenkinson, who has also represented Finland at U19 level due to his mother's nationality.
"There is a real togetherness and the spirit in the squad is something I haven’t experienced at international level before.
"That is a really positive sign and we are really confident that we can do well and obviously we don’t want to get carried away, but I think people will see from Thursday night that we’ve got a good chance in the summer.
"Portugal are a team we are playing in the summer so it was nice to get one-up on them and I think pretty much they had their strongest squad out and their best team.
"I think it’s a very good sign, we looked very comfortable and I think we were only hitting seven out of ten as a team. We can play even better than that so it’s really positive."
England’s last two trips to the Euro U21 Finals in 2013 and 2011 saw the squad knocked out at the group stage without a win, despite qualifying with aplomb on both occasions.
And while Jenkinson knows it will be tough in Czech Republic next summer with Portugal, Italy and Sweden in their group, he refuses to read too much into what happened in both Israel and Denmark to Stuart Pearce’s men.
"We can’t get carried away. Obviously we’ve had discussions about it ourselves but we can’t look at the past and look at what previous teams have done," he added.
"We’ve got our own destiny, we’ve got our own history to make as a team. We can’t worry about what has happened in the past.
"We are our own team now, we are playing with confidence so we’ve just got to take confidence from nights like Thursday and play with the freedom we’ve been playing with."
Beneath that togetherness and team spirit though, there is a fierce competition for places in Southgate’s line-up between the group of players who have featured over the last 13 months.
With a 23-man squad limit for the Finals next June and just three more games to be played before then, Jenkinson revealed the standard of training hasn’t dropped once as every player looks to impress their boss.
"Everyone wants to be in the team and the training sessions are of a very high quality," he said.
"Everyone is busting a gut because everyone wants to be playing. It’s a massive tournament in the summer and, like I said, everyone wants to be in that team.
"We’ve been trying to stake our claim for a place in all the qualifying games, but I suppose it does really start now.
"These are the big games. We’ve got a game against France [on Monday] and obviously we have just played Portugal.
"These are the big games that you really want to be impressing in and as a team we’ve definitely done that."
Watch the highlights of England Under-21s' win over Portugal at Turf Moor.