The Magpies' captures of Fabian Schar from Deportivo La Coruna and Yoshinori Muto from Mainz 05 this week follow the arrivals of Ki Sung-yeung and goalkeeper Martin Dubravka's permanent moves to the club, as Rafael Benitez's team step up their preparations for the new campaign.
Speaking to the Newcastle Chronicle ahead of the side's pre-season camp in Portugal, Shelvey admitted that Newcastle's "very young team" must stick together to remain in the league's top half this season.
"I think all we need to do is stick together in and around the group," the midfielder said.
"It's a very, very young team and we're inexperienced in terms of Premier League games and stuff like that but I think the main message that we need to send round to the fans and the players is that we need to fight as one."
Newcastle begin their league campaign against Tottenham Hotspur at St James' Park.