Proto-Namican is still a rather unreasonable target, let's start with Proto-Namicish (Namican proper):

*p *t *c *ṭ *č *k *k° *ʔ
*b *d *ʒ *ḍ *ǯ *g *g°
*m *n *ṇ *ñ *ŋ
*v *s *z *ṣ *ž *x *x° *h
*w *l *ṛ *γ

*i *ü *e *a *u *i· *ü· *e· *a· *u·
*ɛ̣ *ạ *ọ (These vowels probably were long and backed)

Here are thus some preliminary sound changes to Namic proper:
(T = voiceless stops, D = voiced stops)

ṣ -> ł̣
{i ü u} -> 0 / T_C(C)(C)V
x -> š / _{i ü e a}
xy -> š
e -> ä / Cγ_
u -> o / Cγ_
ɛ̣ ạ ọ -> e· a· o·
ä· -> a·
ü -> ö
i·ʔ ü·ʔ u·ʔ e·ʔ a·ʔ o·ʔ-> i ü u e a o / _#, _C
iγ üγ uγ eγ aγ oγ -> i· ü· u· e· a· o· / _C, _#
{t c ṭ č k k°} -> {tʰ cʰ ṭʰ čʰ kʰ kʰ°} / _Vh, _Vx, _Vx°
{t c ṭ č k k°} -> {tʰ cʰ ṭʰ čʰ kʰ kʰ°} / _h
{t ṭ k} -> {tt ṭṭ kk} / ʔ_
ʔ -> 0
γ -> ž / _{i ü e ö ä}
γ -> w / _{u o a}
γ -> 0
kʰ° -> v
ṇ -> ŋ / _{u o a}, {u o a}_
ṇ -> n
x -> h
h -> 0
v -> 0 / _i
v -> w 
z and ž become less fricated over time
DV -> TV̀
VD -> V̀T
D -> T

And some examples:

ne·ʔmik -> nemik [nɛmɪk] 'Namic' pn.
u·žγu-n -> uoʒon [uːj̟ɔn] 'to go' v
ʔitagu -> ttakù [tːɐɡʊ̀] 'clap' n.
xeži -> sceʒi [ʃɛj̟ɪ] 'breath' n.
xüwide-n -> scọwitèn [ʃœwɪdɛ̀n] 'to disappear, to vanish' v.
ṣiγu-n -> ḷiwun [ꞎɪwʊn] 'to torture, to make someone bleed' v.

And I somehow managed to completely forgot to post Namic phonology, so here it is:

p t ʦ ʈ ʧ k kʷ <p t ts ṭ c k kw>
tː ʈː kː <tt ṭṭ kk>
tʰ ʦʰ ʈʰ ʧʰ kʰ <th tsh ṭh ch kh>
m n ɲ ŋ ŋʷ <m n ñ ŋ ŋw>
s ꞎ ʃ xʷ <s ḷ sc hw>
l z ɻ ʒ w <l z r ʒ w>

ɪ ʊ ɛ œ ɔ æ ɐ <i u e ọ o æ a>
iː yː uː eː oː aː <ie ọy uo ei ou aa>