The interpretation timeline
Mark 16:15 Douay-Rheims

And he said to them: Go ye into the whole world, and preach the gospel to every creature.

A.D. 604 – 1863 5 witnesses

Patristic

before A.D. 750
604
A.D.
Gregory the Great Patristic
c. A.D. 540–604
“(ubi sup.) After rebuking the hardness of their hearts, let us hear the words of advice which He speaks. For it goes on: Go ye into all the world, and preach the Gospel to every creature. Every man must be understood by every creature; for man partakes something of every creature; he has existence as have stones, life as trees, feeling as animals, understanding as have Angels. For the Gospel is preached to every creature, because he is taught by it, for whose sake all are created, whom all things are in some way like, and from whom therefore they are not alien. By the name of every creature also every nation of the Gentiles may be meant. For it had been said before, Go not into the way of the Gentiles. (Matt. 10:5) But now it is said, Preach the Gospel to every creature, so that the preaching of the Apostles which was thrust aside by Judæa, might be an assistance to us, since Judæa had haughtily rejected it, thus witnessing to her own damnation.”
Source

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“And He said unto them , Go ye into the whole worlds and preach the Gospel to every creature. He said this not on Easter day, when He appeared to the Eleven as they sat at meat, but afterwards, when He showed Himself to them and others on a mountain of Galilee, as it is in S. Matt, xxviii. 16, &c. Or it may be that He committed this chief and peculiar office of preaching the Gospel to the Apostles more than once. Go ye into the whole world , that is to say, not into Judaea only, as ye have done hitherto, but up and down in all directions throughout the world. For it does not seem probable that a few Apostles should have traversed and converted the whole world, especially because in America, lately discovered, no traces of the faith of Christ have been found. Every creature , i.e., to all nations, as it is in Matt xxviii. 19”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“He that believeth,.... Not notionally only, or that gives a bare assent to the truth of the Gospel; but spiritually, who sees Christ, his need of him, and the worth and excellency, suitableness and fulness of him; who comes to him as a poor perishing sinner, and ventures on him, and commits himself to him, and lives upon him; believing alone in him, and expecting life and salvation alone by him: and is baptized; faith must precede baptism, as these words of Christ, and Scripture examples show; and such as have it, ought to make a profession of it, and be baptized; and in which way it is that faith discovers itself, and works by love to Christ; namely, in observing his commands, and this among the rest: shall be saved, such receive the remission of their sins a justifying righteousness, the privilege of adoption, a right and meetness for heaven now, and shall be saved in Christ, with an everlasting salvation; not that either faith or baptism, are the procuring causes of salvation: not faith, for Christ is the author of salvation; and faith is the grace that looks to him for it, receives the assurance of it now, and that will be the end of it hereafter: faith and eternal life are so connected together, that he that has the one, shall have the other; and it is descriptive of the person that shall enjoy it: and baptism, though it is said to save by the resurrection of Christ, as it is a means of leading faith to Christ's resurrection for justification, yet has no casual influence upon salvation; it is not essential to it; the thief on the cross, went to heaven without it, and Simon Magus to hell with it; but it is the duty of every one that believes, and he that truly believes, ought to be baptized, and prove the truth of his faith, by his obedience to Christ, and such shall be saved: but he that believeth not shall be damned; such are here chiefly designed, who, are favoured with the Gospel revelation; but either deny it, reject and despise it, or neglect it, and are disobedient to it; whose guilt is the greater, and whose punishment and damnation will be the more intolerable; even more so, than that of Sodom and Gomorrha, Tyre and Sidon, or any of the Gentiles that perish without the law, and the knowledge of the Gospel; and also such are meant, who are finally unbelievers, who live and die in a state of impenitence and unbelief; otherwise, one that believes not today, may believe tomorrow, and be saved.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Go ye into all the world - See on Mat 28:19 (note). And preach the Gospel to every creature - Proclaim the glad tidings - of Christ crucified; and raised from the dead - to all the creation, πασῃ τῃ κτισει - to the Gentile world; for in this sense בריות berioth, is often understood among the rabbins; because He, through the grace of God, hath tasted death for Every man, Heb 2:9. And on the rejection of the Gospel by the Jews, it was sent to the whole Gentile world.”
Source
1863
A.D.
1796–1863
“To disbelieve the gospel preached by its lawful heralds, implies the rejection of divine authority, and is matter of just condemnation.”
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.