According to your Xorg.0.log you are using the fbdev driver now, so no wonder there’s no hardware 3D support.
You have the follwing lines in there:
42.856] (EE) [drm] KMS not enabled 42.856] (EE) [drm] KMS not enabled
So you somehow have disabled kernel mode setting (KMS), which is needed by nouveau.
Maybe that’s a leftover of your try to install the nvidia driver.
Please post the output of the following:
grep nouveau /etc/modprobe.d/*
and
cat /proc/cmdline