The 18-year-old full-back came on as a half-time substitute in the friendly on Wednesday, replacing one of his boyhood heroes - Ashley Cole.
Asked if he expected international recognition to come so early in his career, the teenager said: "No way. I wouldn't even have thought I would even be getting mentioned to be going away with the senior squad.
"But it has happened and I enjoyed every minute of it and I will never forget the moment I came on.
"It has been an emotional week and the best week of my life. I will never forget this week."
With Leighton Baines' World Cup place all but guaranteed, Shaw faces a battle to make the trip to Brazil ahead of England's fifth most capped player, Cole.
"I am not thinking about that yet," Shaw said when asked about his World Cup chances.
"Obviously I did play a part in that game but there are important games coming up for my club.
"Hopefully if I keep putting in good performances then Roy will have a hard decision to make.
The Southampton defender admitted he was nervous when Roy Hodgson told him on Wednesday afternoon he would make his debut and revealed Frank Lampard gave him some valuable words of advice.
"As soon as I got on the pitch, all the nerves went and I enjoyed every bit of it," he told Southampton's official YouTube channel. "I just tried to focus on playing my normal game.
"I had a word with Frank Lampard before the game and he said 'I have been in this situation before, you're 18 years old, I know how you are feeling. You are going to feel nervous but make sure you enjoy every minute of it and just play how you've been playing for your club'."