non-mechanical release aids have been around for millenniums, let alone centuries. there are basically two types, ledge and finger pressure. i've used both for more than a few decades, in recurve unlimited competition.
all ledge releases are loosely based on the asiatic thumb ring, where the release catches the string and is held onto it by string pressure (during the draw) and leverage (the angle of the ledge). changing the lever angle with a thumb or hand or wrist motion allows the release ledge to slip off the string. the most popular, back in the 60's-70's was the "6-gold" release aid.
finger pressure release aids, such as the one mudd made, uses a flap of leather strap or thick cord wrapped once around the bowstring and the string hand thumb pinches the strap/rope tightly to prevent release. lessening thumb pressure allows the string to slip free of the release strap/rope.
in the late 60's i made and used a variation of the thumb rope release . it used a 1/4" braid marine rope looped into a 1/2" id clear flex plastic tubing that was a good 3/4" od. the rear of the tube used a round concho to hold the rope in place with a big knot. the rope loop went around the bowstring and under the nock (as does with mudd's strap) and was held by the thumb to the side of the tubing. where the rope met the tubing, the tubing was slightly dished by melting it with a hot 1/4" rod, so that the rope would somewhat lie within the dish - this provided added mechanical advantage for ease of drawing as less thumb pressure was required.
any trigger activated release is mechanical, and there are simple but clever ways to combine a ledge and rope to create an effective mechanical release aid.
the chief benefit of a properly used and executed release aid is the "surprise" of the release - you never know when it's going off and therefore you don't anticipate the shot. in addition, the small area of contact between the ledge or strap/rope makes for a very fast and clean release.
release aids look simple, but require far more adaptation and mental control than fingers on the bowstring.