You concluded this based upon what evidence? Expand upon these logical deductions if you please, as it's clear very few people think the same way you do with regards to this matter.
I do, in fact, understand each and every one of those concepts, but they don't answer the statements. Many plausible outcomes from observations? I'm pretty sure a cylinder and a sphere look pretty different. Maths isn't my strongest subject, but even I can tell the difference. Maths, in my experience, doesn't tend to lie, and trigonometry performed by several civilisations across time, has resulted in an agreed upon round earth? You can't even pull the "different trigonometry" line, as your sun doesn't orbit the earth, in any sense of the word. I'll just leave the questions at that for now, that should be plenty.
Also, "the", not "teh"...