Even based on public policy (and ignoring how their private actions), US democrats are closer to “global centre” but still in many cases to the right of centre.
On economic issues, the Democrat mainstream is center to center right compared to Europe. But overlook that social democracies in Europe went through a long conservative retrenchment after the 1960s and 1970s. Look at the corporate tax rates in Sweden.
If you want to decide the center yourself on every issue then you’d have to take true and accurate surveys of a global population and then stratify them for their various biases (religious or cultural or whatever) then further stratify each cohort by age, family, gender, sexual orientation, and many other variables. The idealogical center to your surveys will just be the mode for your various questions, if true
Now