In their first match since being crowned world champions for the second time, La Roja were hit by an English storm just before half-time as Anthony Gordon and Harry Kane put the Three Lions in front.
But the European champions responded as Alex Baena levelled before Mikel Oyarzabal struck the winner, just as he did when the sides met in the final of EURO 2024.
"What this generation of footballers is achieving has great merit. They are constantly striving to improve," said De la Fuente. "The statistics speak for themselves.
"It is incredibly difficult what Spain are doing. We will approach the next match against Croatia as if it were our last. These players always want to keep improving."
Spain got off to the perfect start when Lamine Yamal robbed Marc Guehi before slotting home.
Yamal could be back in London next month as he dreams of winning the Ballon d'Or for the first time.
'Lucky to have' Lamine
"His performance was exceptional; we are lucky to have him," added De la Fuente of the 19-year-old.
"He plays exactly as the match demands, utilising both his own attributes and those of his teammates."