In other words: “Are there people who believe in spirits and engage in magical thinking and mysterious rituals?”
Yes. Just about every person who follows a religion today can be described this way, I suppose. Using this definition, one person’s witch is another person’s catholic.
Were there ever witches in the sense of a person who believed they were in league with the devil, who thought they could fly through the night air, and meet to celebrate a Black Mass? I doubt such tales are any more than fanciful stories intended to frighten the ignorant, or at the worst, frightened lies offered as a result of torture.
The papal bull, Summis desiderantes affectibus, was essentially a letter of support for the Inquisitors Institoris and Sprenger (both of the Dominican order) to help them with their work in Germany, where they were facing opposition from both secular and clerical officials. It was intended to quiet any complaints from those parties. Unfortunately, it also had the consequence of “establishing once and for all that the Inquisition against witches had full papal approval” (Russell, 1972). The (no-doubt) unintended result of this approval was the introduction of a general sanction in the minds of many for all kinds of bloodletting and torture in the years to come.
The papal bull had little direct connection to the book, Malleus Maleficarum, since it was issued 2 years prior to the publication of the book, but by its very nature lended credibility to the awful tome.
While the papal bull of Innocent VIII stood out as the most emphatic statement in support of the fight against witches, it was only the last in a long line of papal bulls that set the stage for increasingly severe actions against heretics, sorcerers, and practitioners of black magic, which the Church apparently suspected, lurked behind every corner.
But would it be considered authoritative today? Hardly. So put down your thumbscrews, sell your rack, and maybe consider a more sedate hobby, like pinning live butterflies to styrofoam.