Sounds like you went on the wrong skills course to be honest.
For reference, i’ve been riding for about 10 years and i’m still terrible compared to some people. There will always be someone quicker than you so don’t let that ruin your enjoyment.
Work on one skill at a time, be it foot positioning, looking ahead through the corners, berms, manuals as you cant conquer everything all at once.
Keep working on fitness, at a reasonable pace I will complete Monkey and FTD in around 90 minutes on an average day. Riding with my quicker XC friends I can do it in less.