For instance: a first-rate ship of the line would have 100+ guns. These could be any configuration of actual firepower and weight of metal for benefit of structural integrity and weight distribution (fifty 18-pounders, thirty 12-pdrs, eighteen 6-prds, and two long nines for instance), and later ships of course were built strong enough to employ greater guns, or else were making use of the much lighter, much closer-range and smaller-crewed carronades.

All of this is context for the question I'm now asking:

could a sloop-of-war or corvette (more or less the bottom of the rating system, though not the VERY bottom) of the end of that period have held its own against a first rate of the beginning?

Sure, the USS Constellation of the 1850's might not have as much armor just by dint of less decking, but in turn being made at such a time that larger guns were being used, would she not have had stronger planking that might guard against the smaller/less powerful guns of the Napoleonic era? Let's take HMS Victory, which was built around 90 years prior but updated at the turn of the century and utilized throughout the Napoleonic Wars.

Add in the greater speed and maneuverability of the Constellation and the fact that it would be difficult to fire effectively down from the higher gun decks of the Victory --- not to mention SIZE! The 22(ish) gun Constellation was about the same length on deck as the Victory, about twice the length (and proportionately around 3x the size/displacement) of a similarly rated ship from Victory's era. (The USS Wasp of 1814 is a good comparisson.)

So, our too-tiny-to-be-rated Constellation is extraordinarily large compared to its similarly-rated Wasp, and well-armed with its parrott rifles and howitzers, pitted against the Victory with four times as many guns and decks but of inferior firepower and build just by dint of progress over time...

I'm not at a point of calculating rate of fire, explosive power, or actual weight of metal, nor even sailing advantages, but...

I think Constellation could take her.

A scene on Lake Ontario, 1813.

The inscription reads:

United States Sloop of War General Pike, Commodore Chauncey and the British Sloop of War Wolf, sir James Yeo, Preparing for action. Sept. 28th, 1813. Published and Sold by Shelton and Kensett, Chesire Con., Nov. 1st, 1813.

USS LANCASTER (1858), a screw sloop of war, cruises under steam in waters off New York following a deployment to the Mediterranean.

She a participated in the Civil war and the Spanish-American War. She was decommissioned and recommissioned three times. Years of service: 1859-1867; 1869-1889; 1891-1897; 1898-1915.

"Her gold eagle figurehead is now displayed at the Mariners’ Museum in Newport News, Virginia.”

Photographed in 1889.

The "Kearsarge" at Boulogne by Edouard Manet, 1864.

The first lieutenant was of the medium stature, a suitable height for a sloop of war, a spare figure, of about forty years of age; he had but one eye, and that eye was as odd a one as the captain’s. There was in it, however, unlike the captain’s, an infinite deal of humour, and when he cocked it, as he constantly did, it almost spoke.

— Frederick Marryat, The Naval Officer (Frank Mildmay)

The first ship to bear the name Maryland was a sloop-of-war that served during the Quasi-War with France. She was launched on June 3,1799 and commissioned that August with Captain John Rodgers in command. Her crew consisted of 180 officers and men and she carried 20 9 pounder guns and 6 6 pounders. 

Maryland departed Baltimore in September bound for the Suriname station. She arrived there on October 1 and proceeded to cruise from French Guiana to Curacao protecting American shipping from French privateers. While there she captured the American schooner Clarissa, a slave trader without papers, on January 4, 1800. On July 26 she fell in with and then recaptured the Gloria da Mar, a Portuguese brig which had been captured by French privateers only 13 days earlier.

Maryland departed her station bound for home in August, having served since December 1799 as the only American vessel on the Suriname station. Sailing by the way of St. Kitts and St. Thomas, she escorted a large convoy of British and American merchantmen, as well as captured the Aerial, an American merchantman without papers on September 2.

She arrived Baltimore 1 October for repairs.

Maryland again departed Baltimore on March 22,1801 with Congressman John Dawson of Virginia aboard. Dawson was President Adams’ designated bearer of the amended and ratified Treaty of Mortefontaine with France. Maryland arrived in Havre de Grâce, France, in early May where she remained until 15 July, when, because of difficulties in obtaining ratification, she was released by Congressman Dawson and sent home.