The universe is curved

So it is. It's difficult to find straight lines in the cosmos. Even if we draw a straight line on the planet's surface, it is curved due to the planet's spherical shape. I wonder if any scientist or mathematician ever though about  formulas and measurements being of a lineal nature.  An example:  Let's say speed.  The speed of a human running is that of around 30km/h. the speed of sound is that of around 1,000 km/h. The speed of light is that of 1,080,000,000 km/h.  It is very clear which speed is greater, and the relativity between each speed.  This is because these type of mathematical measurements based on value, correspond to a line in which one value is either greater or lesser than the other, and the line in which these values are placed is straight.
What if we where to place these values on a curved line, or better yet, on a line of a large circle. We could then get variations on the relative distance or difference between these speeds. And in the case of a circle, a very fast speed in comparison to a very slow speed could eventually overlap. So mathematics is based on constants and straight lines. But what if these were traits that belong only to human thinking, and these straight lines and constants don't really exist in the universe?