Indeed, I was worrying about the filesize of the BMP files too.
I can download your images now, so I will comment on them individually.
Level 105
I assume you're going for a Nintendo-esque style. The level in general, however, reminds me of a spiced-up 105 edit. You've used the same set of sprites SMW did in 105 -- namely the sliding koopas and the Banzai Bill. Sprite sets aside, most of the enemies do feel like they're an afterthought. The sliding koopas after the first set of pipes, for example, will just casually slide off before Mario can encounter them.
Moreover, fairly "common" enemies like Koopas are used here which isn't usually the best idea. In 105, Mario had to dodge Banzai Bills in a variety of situations, such as leaning down into the ground, or jumping over them. In your hack, most enemies can be easily jumped over. This'll be more of a problem in later levels if you plan on using this concept as it usually results in cheap difficulty. I would recommend using some different sprites in later levels to vary up the gameplay a tad.
However, criticism aside, some of your screens in this level have an interesting setup, for example the use of the turn block bridges in the second half of your level and the piranha plant setups in the beginning. Overall, the level is nice in parts but suffers from 'filler' segments which ultimately drag the level down.
Level 106
This level looks more promising than the first! The first part of the level seems a little saturated with enemies though -- particularly the jumping koopas in between the piranha plants which aren't really necessary. It's often best to use sparing amounts of sprites in more threatening situations for Mario rather than saturating the level with goombas and koopas which Mario can easily jump over. As a minor point, the 1up mushroom with the walljumping seems out of place. I feel it's better being added after the message box in the second half which formally explains the walljump mechanic better. Finally, the kicking koopa shell mechanic seems interesting, but is it perhaps too hard for the second level? Overall, this level's a lot better than the first. There's still an issue of 'filler' sections being added in the level but to a lot less extent than the first level.
Sorry if I seem really negative during those reviews! I'm just trying to help, that's all.