Yes, Diderot (first name Denis) is accessible to “less smart people”. He was a big figure of Enlightenment Philosophers and well as for what has become “Laïcité” (separation of State and Church) in France and most francophone countries. The famous quote “We swallow comfortably lies that arrange us but drink hardly truths that bother us”.
Diderot’s position on religious beliefs evolved over time. Dedicated to an ecclesiastical career, he evolved towards theism, deism, and finally subscribe to materialist ideas. His main writings were Philosophical Thoughts and The Letter on the blind for the use of those who see.
His famous friends were (listing 3)
Jean-Jacques Rousseau another big figure who influenced Immanuel Kant etc.,
Paul Henry d’Holbach that some say to be the 2nd real Atheist in History after Abbé Meslier (the 1st Atheist who said “religion will stop only if all the nobles are hanged with the guts of priests”),
Voltaire (“religion has existed since the first hypocrite met the first fool”) …
A contemporary french philosopher that you may like to read is Michel Onfray.