Evolution or Devolution?

[Welsh cake]

It is a widely held belief that life began with a simple single celled organism and over time the descendants of that first lifeform changed in various ways and became more complex to produce all the different forms of life we have today. This process in called evolution.

Read up on evolution, go Wikipedia even. Then you'll know it's not actually a "belief", but scientific fact, and maybe, just maybe you'll save yourself the time and embarrassment.

An alternate explanation is found in the Bible.

Even if I accept that ridiculous claim, your failure to prove God being the stumbling block of your argument, the Bible has no explanatory power or consistency; if it did it wouldn't need apologists making excuses for it. What kind of all-powerful God needs Ray Comfort's defence? You tell me.

Genesis 5 shows us that originally it was normal for people to live to be over 900 years old.

Why should we care what the Bible says? Chapter Four in "The Iron Man" by Ted Hughes tells us that a space-bat-angel-dragon, the size of Australia, came to Earth from Constellation of Orion. It does not show us how humans had a longer lifespans in comparison - it asserts that people lived to these biologically improbable ages. Unless you find circular reasoning such as "the Bible proves the Bible" convincing no one in their right sane mind is going to accept that fantasy as truth.

In recent years improvements in sanitation, nutrition, and medicine have enabled people to live longer that in the past but this doesn't mean that our normal lifespan has increased.

You need to read up on Reliability theory particularly where it concerns biological aging and longevity. If you had you would have known there's no theoretical upper limit to human longevity, or a definitive maximal human lifespan that says any human being anywhere ever lived to 900 years of age. I suppose you'll argue next that a lack of God in our lives is responsible for this? >.> At this point you really have to provide evidence that people ever lived longer in the first instance otherwise you'll end up making one nonsensical statement after another.

But is this change the result of evolution or devolution? Are we seeing a process that began with simple lifeforms and has led to the development of more complex life or are we seeing a process of degeneration from an original state of prefection?

You seem to think so. Demonstrate it.

Until you do, we're done here.