There is no way anyone can make a accurate diagnosis of that cam due to the piccies being blurred.
If two of the hydraulic followers were hard to get out, have a close look at the surface they run on, you may well find it is cored to buggery.
This wil certainly give you constant noise if bad enough to jam tappets them only freeeing off each time they are whacked by the cam and pushed down again, my suspicion being if they are jamming without fully rising again due to the valve spring pressure, the valves will of course be open.
The cam is in constant contact normally, albeit very gentle contact when off lobe, then gently pushes open, but if jamming you get a sudden clout as the lobe hits the bucket each time.
The cam may well not be worn but it is crucial that the followers slide freely.
tabetha