The 747 was an amazing engineering marvel. They started designing it in '65, the first one rolled off the production line in '68, and they were still making and selling them right up to 2023.
I have a book here somewhere that talks about how so many of the design decisions were based on cold hard physics facts combined with engineering pragmatism. They needed to run the engine at peak efficiency, and the tradeoff between air density and air temperature set the cruising altitude to ~35,000 feet. They knew they didn't know enough to be able to build a supersonic plane, so that set the top speed at just under mach 1 at 35,000 feet. They wanted to carry 2-3 times as many passengers as the 707 which set the payload and the all up weight. It needed to go slow enough to land safely at typical airport altitudes, which set the wing loading and given the weight the wing area. It needed to be as efficient as possible which meant a high aspect ratio, but given the required wing area and the available engineering capability for wing spars and aluminum construction that set the wing span.
It was hard engineering tradeoffs like that which then set a whole bunch of aviation standards. Runway lengths, terminal and jetway heights, landing approach speeds - all those types of "standards" which still exist today in airports around the globe, are heavily influenced by the 747 and it's design parameters. Cessna 172s flying into international airports have to fly their landing approach way faster than usual for that type of plane because _everybody_ flies approaches at 747 speeds.
That is not today's Boeing.