There’s a lot to unpack.
a) How long does it take to build a civilization?
Did it take a single generation?
Can it be done by people from our time only, or will it take people from our time and several further generations from here?
b) Fighting for freedom.
What does that mean? Fighting for freedom from what?
c) Grand scale.
Which times have humans have built civilizations and fought for freedom on grand scales that we can compare to?
How grand was it?
Most wars and battles are skirmishes magnified by history. The only exceptions I can think of right now is the 20th century. In the 20th century, the industrial revolution had taken over and human were treated as exchangeable statistics with massive people-moving efforts by strict hierarchies.
Maybe there are some particular fights for freedom/civilization building examples you have in mind that I can compare to.
“Do you believe people from our time are presently as capable of building civilizations and fighting for freedom on a grand scale as those from history if we were challenged to do so by necessity?”