Was the original "Pink Panther" movie intended to be a comedy?

From NNDB:

Edwards' most famous work, The Pink Panther, was released in 1963, with Peter Sellers as Inspector Jacques Clouseau. The part had originally been cast with Peter Ustinov, but that actor reneged at the last minute, and Sellers stepped in, with his suggestion that the character be "bumbling", which, of course, changed not just the character, but the nature of film comedy.

And from a Review by Clarenc Beaks:

The Pink Panther (1963) began life as a star-studded caper comedy intended to be anchored by David Niven as the debonair jewel thief Sir Charles Lytton, aka "The Phantom," a man audacious enough to carry on an affair with the wife of his tireless, if thoroughly inept, pursuer, Inspector Jacques Clouseau. And had Peter Ustinov, originally cast as Clouseau (and, coincidentally, batman to the higher-ranking Niven in World War II), not backed out of the production, following Ava Gardner's lead (who had been cast as Clouseau's philandering spouse), it's entirely possible that there would have been no Pink Panther franchise (though a great thespian, Ustinov was hardly anyone's idea of an explosive comedic talent). But when Peter Sellers came on board as the incompetent inspector, the picture was suddenly given a raucously funny performer who easily could run away with the proceedings.

So it seems it was intended to be a comedy from the beginning, but quite a different style of comedy than what it became once Sellers got involved.

I do recall the first Pink Panther movie being less slapstick in its approach, a more subtle performance from the cast - but I would find it hard to believe that they set out to make a serious movie and ended up with a comedy.

No matter how big the star, I simply don't believe they would let someone completely revise the genre of a movie like that. Peter Sellers was almost exclusively known as a comedic actor, in both Radio and Movies, it was very much the exception when he played serious parts. His write up on IMDB starts "Often credited as the greatest comedian of all time".

I have no evidence, but I just don't find it credible.

Yes, I saw documentaries with Blake Edwards and he knows lot about comedy and visual gags. I'm sure he knew he was doing a comedy.

The Spanish documentary "Y usted ... ¿de que se ríe?" contains an interview with Blake Edwards about comedy.

In deciding whether the film was originally planned as a comedy you might look, for instance at the names of the Director, the screenwriter, and the cast.

How many films did Peter Sellers make which were not comedies, for instance? His entire reputation was in comedy, from the time of his earliest beginnings in radio with 'The Goon Show'.

Blake Edwards was not known for making Shakespearean drama, nor even for making contemporary drama. He was not Irwin Allen, who directed 'Towering Inferno' and 'The Poseidon Adventure'. Nor was he Cecil B DeMille.

It is a mistake to suppose that the lead actor, Sellers, can re-write the screenplay. Only the director of the film can do that; and if the actors wish to make changes, this cannot be done without the agreement and support of the director.

Sellers had the ability to make a humorous screenplay funnier in performance than it might appear on the written page; but unless the director was making a comedy, Sellers had no chance of getting laughs, if that was not Edwards' intention.

Then again, why hire Sellers at all, unless you were making a comedy?

Here's what you need to know:

For example, when writer/director Blake Edwards first came up with the idea for the first “Pink Panther” outing, he envisioned a spoof of a heist film, with veteran star David Niven playing a suave jewel thief, much like Cary Grant in “To Catch A Thief.”

https://www.bestmoviesbyfarr.com/articles/the-pink-panther/2016/03

As he (Edwards) put it: “For years I'd been getting bits of what I wanted into films, as writer or director...but I had never had an area in which to exploit my ideas to the full. Then along came Peter, a walking storehouse of madness, a ham with an almost surrealist approach to the insanity of things, and we found an immediate affinity.