Eddie Jones will be without a large chunk of his first-choice squad for the two-Test trip to South America due to them being selected for the British and Irish Lions tour of New Zealand.
The likes of Tom Curry, Ben Curry, Joe Cokanasiga, Nick Isiekwe and Nathan Earle have all come into the squad as a result, and Robshaw has been encouraged by what he saw during Sunday's 28-14 win over the Barbarians at Twickenham.
"I have been really impressed with everyone, whether they have been 18 or 32 or something like that. It was a first hit-out for a lot of guys in an England shirt, and sometimes that can be a bit overwhelming, especially being at Twickenham in front of a good crowd against a star-studded team. But it was perfect preparation for us going to Argentina," he told reporters.
"Two weeks ago it made me feel old when I looked around, and I must have been the oldest player by about seven years! It keeps you on your toes, I tell you that. There are about three or four [teenagers] in the squad now. They are extremely energetic, they want to get involved and they want to learn. That's the important thing.
"They want to soak up information, whether it is from players or coaches, and they want to improve and really enjoy the setup. I think everyone has come in and done themselves proud. It is about trying to kick on from that Ireland game, because obviously that didn't go to plan. You never want to lose two games on the bounce, and that was an important message for us going into [the Barbarians match]."
England's first Test of their Argentina tour comes on Sunday, June 11 in San Juan.