If This Is A Consular Ship, Where Is The Ambassador?

OK, that title is not really related with what I'm writing here but it's close enough.

For years now archeologists have unearthed various artifacts from ancient civilisations, especially of the Aztecs and the Mayans. Some of these artifacts are intriguing such as airplane-shaped objects, 'helmeted' figurines, drawings of a king inside some kind of rocket-propelled vehicles and hieroglyphs of planes, submarines and helicopters. Others even tried to point out higher radioactive counts at certain ancient ruins as evidence of a nuclear war some time in the past....

For some, these are the evidence that ancient civilisations were not as 'backwards' as they were usually portrayed. Still for some, this means Earth were once frequently visited by extraterrestrial beings who shared their superior tech with the ancients.

While I'm quite open about aliens and UFOs, I'm actually quite sceptical about these trinkets, paintings and carvings being the evidence that ancient civilisation tech were just as advanced as the 20th-21st centuries'. I mean come on, we have 65 million (and even older) fossilised bones as the evidence of the existence of dinosaurs but not one of the remains of the actual so-called ancient airplanes, subs or rockets has ever been found. So if they were real, where are the remains? Granted that since they are made of metal, they might have corroded down to nothing from the time of the civilisation's decline until its discovery. But again, not even ONE? I mean, even remains of Egyptian chariots have been found in the Red Sea....To draw an analogy; should humans disappear overnight ( like shown in Life After People), the only evidence of our usage of planes, trains and automobiles are scale models and toys!

Another reason which makes me sceptical is that these people only shows photos of 'airplanes' and 'rockets' but not one land vehicles such as automobiles. So it could be either the ancients were so advanced that there is no need for land vehicles (so how do they commute from house to work - flying cars like airspeeders in Star Wars?); they somewhat look like the German army during WW2 (advanced aircraft and tanks but  most of the artillery and support units were still horse-drawn) or that they (the theorists) actually drew the wrong conclusion?

So, to paraphrase Darth Vader from Star Wars Episode IV :  A New Hope; "If the ancients use planes to commute, where are the remains..and where is the airport?"