IMHO, a noticeable noise is worth investigating, especially if it
becomes more audible over time; it may mean a
component is loose, and catching it early could save big expenses later.
Without listening to the engine, none
of us could say whether the noise you're hearing is "normal" or not. Nor
did you say WHEN the noise is
most noticeable, ie, when idling with the hood up, when accelerating, on
hills, when cold, etc, etc..

A little lifter clicking noise may be acceptable with solid lifters, but
you really shouldn't be getting particularly
noticeable noise from only one or two of your hydraulic lifters. If it
IS a lifter, that's easily remedied.
A definite tapping or knocking is not a good sign, but the "tapping"
noise could be
coming from something external like a loose flexplate bolt or a loose
spark plug wire, or a waterpump belt,
fuel pump, exhaust manifold or head gasket leak, dented valve cover,
etc, and not from a vital component like
a rod or lifter or valve or piston or timing chain.
You need to determine the general area of the noise, and estimate it's
frequency with respect to the
engine rotation speed (every rotation, every other rotation, etc), then
investigate further (remove the valve
covers, uncouple a spark plug, or whatever) to further pinpoint it and
assess it's threat to the engine.

Get a mechanic to investigate by using a stethoscope to determine the
probable source and go from there.
A hundred or two spent on diagnosis now could save $$$ later, or it
could just give you peace of mind.