Absolutely. Yes.
First let's take a stroll through some of the responses by others, then see what's left to explain.
Can a 2d cross section of you reproduce?
Analogies between dimensions are very useful for introducing the concept of higher dimensions. However analogies—like models—are only useful within a certain domain (e.g. illustration and teaching) and can be invalid or misleading elsewhere.
For example, geometric relations between 2D shapes and 3D solids (e.g. circles and spheres) seem to work out nicely, but that's only because we established geometry to be that way in the first place! Geometry is conceived assuming "Platonic," ideal shapes, divorced from reality on purpose. It doesn't say anything about what actually exists in 2D.
I haven't read up much on the recent evidence about anyons. Even if 2D particles were said to have been "found," I'm doubtful physicists mean "2D" in the way we imagine it. (From a cursory glance it looks like they're talking about fractional or statistical dimensions.)
Now, a common illustration of why 2D "people" can't exist was parodied on Futurama:
How would these beings "eat" if a digestive track would divide them into completely separate halves? (<PERSON>, a theologian and priest, wrote about these hypotheticals nearly 150 years ago, in his seminal fictional work Flatland.)
Anyone who takes this argument seriously though (and Futurama wasn't), might want to re-evaluate their analytical foundations :-) I mean first of all, what a fatally anthropocentric definition of life and reproduction! I could lead us through some mental exercises to conceive what a 2D being might be like, but it's a little off-topic so I'll put it in an appendix.
If a universe existed with 5 spacial dimensions, there can be no such thing as a '3-dimensional version' of an alien creature which exists in the 5 dimensional space.
I didn't take OP's question as asserting 5 spatial dimensions. There exist theories of multiple time dimensions under which we are all cross-sections of at least 5D spacetime, as long as we're defining "existence" in time and "kime" as the coordinates between which our 3-space bodies have been born and deceased.
But regardless, even if OP meant 5 spatial dimensions, that still doesn't rule out existence of 5-beings or their interaction with 3-beings. What could be the case is that we're all 5-beings, but we "3-beings" never developed (or lost) our ability to perceive and move in 5-space—therefore we remain "stuck" in a 3-film of 5-space, but freely moving 5-beings can "cross in" if they'd like.
Finally, there's speculation that there aren't really "kinds" of dimensions. It's just the framework that most pleasingly organizes the "hologram" of the real universe that we're able to perceive using our organs, and also given the systems of knowledge (e.g. 154
mathematics) we've acquired and invented. I'm partial to this belief myself, so I think arguments about space versus time are moot.
Anyway, I'd like to re-emphasize the danger of analogies, pointing this out explicitly: We seem to want to support fiction in Worldbuilding. We also seem to want to adhere to strict "realities" regarding dimensionality. Fine, then. But realities regarding dimensionality do not follow from analogies regarding dimensionality. Dimensions get weird:
Meanwhile, @ProjectApex makes some compelling arguments. First, this thought: Would a 5-being look at a lifeform so primitive that got stuck in a 3-film, and even consider it "alive," much less want to copulate with them? But in the OP's world, they do for some reason, right? So I think we can take it as a given.
But I agree with @ProjectApex that reproductive mechanisms (nay, even just consciousness) would be so different that, a 5-being trying to make sense of the 3-being lifecycle would be like decoding an ancient language. On one hand, they have the physical advantage of being able to study us inside-out (literally). I think what we consider "life" might to them just be a chapter in inorganic 5-chemistry. On the other hand, such an advanced lifeform might have a very progressive take on life, reproduction, and consciousness. It may decide that 3-beings, as limited as they are dimensionally, enjoy a rich world of consciousness, reminiscent of fractals: only increasing in intricacy despite being fixed upon a coordinate. 154