Two men, working separately but simultaneously, are each cited as the originator of the idea of the metric system depending on what source you read. But it took more than 100 years to implement the ideas they suggested.
Research:

Alder, Ken. “The Measure of All Things.” Simon & Schuster. 2003.
Benham, Elizabeth. “Busting Myths About the Metric System.” National Institute of Standards and Technology. Oct. 6, 2020. https://www.nist.gov/blogs/taking-measure/busting-myths-about-metric-system
“Brief History and Use of the English and Metric Systems of Measurement.” The Science Teacher, vol. 36, no. 5, 1969, pp. 39–40. JSTOR, http://www.jstor.org/stable/24151702
Evelyn, John. “The Diary of John Evelyn, Vol. 1.” M. Walter Dunne. 1901. Accessed online: https://www.gutenberg.org/files/41218/41218-h/41218-h.htm#Footnote_49_49
Gilbert, Burnet. “Lives, Characters, and An Address to Posterity.” London. J. Duncan. Accessed online: https://archive.org/details/livescharactersa00burnrich/page/n5/mode/2up
JOHNSON, ART, et al. “MATH ROOTS: The Beginnings of the Metric System.” Mathematics Teaching in the Middle School, vol. 12, no. 5, 2006, pp. 228–31. JSTOR, http://www.jstor.org/stable/41182394
“Biographie Universelle Classique. Biographie Universelle, Ou Dictionnaire Historique, Etc.” Volume 4. 1833. Accessed online: https://www.google.com/books/edition/Biographie_Universelle_Classique_Biograp/lqqTLwFIyCsC?hl=en&gbpv=0
Maestro, Marcello. “Going Metric: How It All Started.” Journal of the History of Ideas, vol. 41, no. 3, 1980, pp. 479–86. JSTOR, https://doi.org/10.2307/2709407
“Origin of the Metric System.” U.S. Metric Association. https://usma.org/origin-of-the-metric-system
Pepys, Samuel “Diary of Samuel Pepys, Complete.” George Bell and Sons. London. 1893. Accessed online: https://www.gutenberg.org/files/4200/4200-h/4200-h.htm
Riebeek, Holli. “Planetary Motion: The History of an Idea That Launched the Scientific Revolution.” Earth Observatory NASA. July 7, 2009. https://earthobservatory.nasa.gov/features/OrbitsHistory
Russell, Cristine. “Congress Inches Away from Metric Conversion.” BioScience, vol. 24, no. 8, 1974, pp. 441–43. JSTOR, http://www.jstor.org/stable/1296850
Speziali, Pierre. “Mouton, Gabriel.” Dictionary of Scientific Biography, edited by Charles Coulston Gillespie. Vol. 9, pp. 554–555. New York. 1974.
Stephen, Leslie. “Dictionary of National ” MacMillan. New York. 1885-1900. Accessed online: https://archive.org/details/dictionaryofnati61stepuoft/page/n11/mode/2up
Wallis, John, Dr. “The Origin of the Royal Society, 1645-1662.” Fordham University Modern History Sourcebook. https://sourcebooks.fordham.edu/mod/1662royalsociety.asp
“Latitude Dependent Changes in Gravitational Acceleration.” UNLV Department of Geosicence. https://pburnley.faculty.unlv.edu/GEOL452_652/gravity/notes/GravityNotes18LatitudeVariations.htm
Wetfall, Richard S. “Mouton, Gabriel.” The Galileo Project. Rice University. http://galileo.rice.edu/Catalog/NewFiles/mouton.html
Britannica, The Editors of Encyclopaedia. "pendulum". Encyclopedia Britannica, 7 May. 2022, https://www.britannica.com/technology/pendulum
Britannica, The Editors of Encyclopaedia. "Imperial units". Encyclopedia Britannica, 10 Nov. 2023, https://www.britannica.com/topic/Imperial-unit
Britannica, The Editors of E "metric system". Encyclopedia Britannica, 17 Nov. 2023, https://www.britannica.com/science/metric-system-measurement
“Metrication in other countries.” U.S. Metric Associatio https://usma.org/metrication-in-other-countries#chart
Ramani, Madhvi. “How France created the metric system.” BBC. Feb. 24, 2022. https://www.bbc.com/travel/article/20180923-how-france-created-the-metric-system
Zupko, Ronald and Chisholm, Lawrence James. "measurement system."Encyclopedia Britannica, 20 Oct. 2023, https://www.britannica.com/science/measurement-system
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