Peter Martyr Vermigli discusses the doctrine of predestination and fall of Adam; notes that, while scripture is silent about it, most early Christian Fathers believed Adam was one of the elect.
Peter Martyr Vermigli, Predestination and Justification: Two Theological Loci (trans. Frank A. James III; The Peter Martyr Library 8; Sixteenth Century Essays & Studies 68; Moscow, Idaho: The Davenant Institute, 2018), 52
Concerning reprobation, if it is related to the first man, God decreed from eternity to create him, that by means of free will and the giving of grace he could have stood, if he wished. God could have given him greater grace so that he would not have fallen, but he did not wish to do so. Whether Adam was in the number of the reprobate or the predestinated cannot be determined from Scripture, although almost all the fathers agree that he was saved, and so belonged to the number of the predestined. Others who were reprobate appeared before God in a mass of perdition and utterly corrupted for God decreed to produce them from the seed of Adam and not elsewhere. Since by his free purpose he would not bestow his mercy on many, a complete refusal, and rejection, followed, by which they are left in the sin they were both with.