Short Answer, No, Louis Daguerre was not the first person to preserve a photograph

Long Answer, depends on how you define photography.

All photography has it's basis in a natural phenomenon called Camera Obscura which has been known since pre-history times. Basically when light is shined through a pinhole it can produce a reversed and inverted image (left to right and upside down) on a surface opposite to the pinhole. Some theorize that Neolithic persons were aware of this phenomenon and used it in rituals and the such. Overtime camera obscura advanced with the introduction of optical lenses and diaphragms to control how much light was let in and box style camera obscures became popular. Primarily this was used for drawings, studying optics or viewing solar eclipses without roasting their irises.

But you're referring to modern photography, and that has its origins in the early 18th century. A German professor named Johann Heinrich Schulze discovered that silver nitrate reacts with light and darkens (most assumed heat caused it to darken, Schulze proved it was light). Schulze made a mixture of chalk, nitric acid and silver which when he put into sunlight with some stencils in front of it, he was able to capture letters in this bottle of chemicals. Now the one problem is is that it wouldn't stop developing if exposed to light and if the bottle was disturbed the image would go away. If you go with an extremely broad definition of photography, something created by the action of light, this could very well be considered the first photographs.

Over the next hundred years people worked off Schulze's work and some progress was made for longer lasting shapes on paper, but it wasn't until 1816 when a French inventor named Nicéphore Niépce was able to permanently capture small images on paper coated in Silver Chloride, but they were inverted and Niépce later destroyed them when they were brought into light and kept developing. His experiments continued and he was eventually able to make some permanent photos, using a process he called Heliography which was actually closer to the first photocopy as his first prints were copies of engravings.

The first ever true real world photography occurred in 1826 when he used a camera obscura with a pewter plate covered in Bitumen of Judea, later washed with a mixture of lavender and white petroleum, to capture View From the Window At Le Gras while not exactly rich with detail it was the first image ever permanently capture onto a physical medium.

Now Daguerre comes into the story. Him and Niépce worked together to create a more viable method of capturing images, as View from the Window of Le Gras took several days to capture. Niépce died in 1830 and Daguerre continued their work, eventually creating the Daguerrotype which was the first commercially available method of preserving images.

So to answer your question, yes photography existed before Daguerre depending on how you define photography. In it's most basic form, photography is creating something through the action of light and that had been done before Daguerre. However photography as an activity that general public could do only came about because of Daguerre who later gave his Daguerretype process away as a gift to the world.

To put it another way, I thought that Daguerre was the first to reveal a photographic process.

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But they seemed to say that scientists knew how to do it, it just took too long and he reduced the exposure time, rather than invent the whole process.

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The difference between inventing the mp3 player and finding out how to go from 1 song to 10,000 songs.