The original three-dimensional work shown in this image is free content because its copyright has expired.
This applies to the United States, where Works published prior to 1978 were copyright protected for a maximum of 75 years. See Circular 1 "COPYRIGHT BASICS" PDF from the U.S. Copyright Office. Works published before 1924 are now in the public domain and also in countries that figure copyright from the date of death of the artist (post mortem auctoris in this case Michelangelo March 6, 1475 – February 18, 1564) and that most commonly run for a period of 50 to 70 years from December 31st of that year.